// Copyright 2012 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/heap/heap.h" #include <cinttypes> #include <iomanip> #include <memory> #include <unordered_map> #include <unordered_set> #include "src/api/api-inl.h" #include "src/base/bits.h" #include "src/base/flags.h" #include "src/base/once.h" #include "src/base/platform/mutex.h" #include "src/base/utils/random-number-generator.h" #include "src/builtins/accessors.h" #include "src/codegen/assembler-inl.h" #include "src/codegen/compilation-cache.h" #include "src/common/globals.h" #include "src/debug/debug.h" #include "src/deoptimizer/deoptimizer.h" #include "src/execution/microtask-queue.h" #include "src/execution/runtime-profiler.h" #include "src/execution/v8threads.h" #include "src/execution/vm-state-inl.h" #include "src/handles/global-handles.h" #include "src/heap/array-buffer-collector.h" #include "src/heap/array-buffer-sweeper.h" #include "src/heap/array-buffer-tracker-inl.h" #include "src/heap/barrier.h" #include "src/heap/code-object-registry.h" #include "src/heap/code-stats.h" #include "src/heap/combined-heap.h" #include "src/heap/concurrent-allocator.h" #include "src/heap/concurrent-marking.h" #include "src/heap/embedder-tracing.h" #include "src/heap/finalization-registry-cleanup-task.h" #include "src/heap/gc-idle-time-handler.h" #include "src/heap/gc-tracer.h" #include "src/heap/heap-controller.h" #include "src/heap/heap-write-barrier-inl.h" #include "src/heap/incremental-marking-inl.h" #include "src/heap/incremental-marking.h" #include "src/heap/large-spaces.h" #include "src/heap/local-heap.h" #include "src/heap/mark-compact-inl.h" #include "src/heap/mark-compact.h" #include "src/heap/memory-chunk-inl.h" #include "src/heap/memory-measurement.h" #include "src/heap/memory-reducer.h" #include "src/heap/object-stats.h" #include "src/heap/objects-visiting-inl.h" #include "src/heap/objects-visiting.h" #include "src/heap/paged-spaces-inl.h" #include "src/heap/read-only-heap.h" #include "src/heap/remembered-set.h" #include "src/heap/safepoint.h" #include "src/heap/scavenge-job.h" #include "src/heap/scavenger-inl.h" #include "src/heap/stress-marking-observer.h" #include "src/heap/stress-scavenge-observer.h" #include "src/heap/sweeper.h" #include "src/init/bootstrapper.h" #include "src/init/v8.h" #include "src/interpreter/interpreter.h" #include "src/logging/log.h" #include "src/numbers/conversions.h" #include "src/objects/data-handler.h" #include "src/objects/feedback-vector.h" #include "src/objects/free-space-inl.h" #include "src/objects/hash-table-inl.h" #include "src/objects/maybe-object.h" #include "src/objects/shared-function-info.h" #include "src/objects/slots-atomic-inl.h" #include "src/objects/slots-inl.h" #include "src/regexp/regexp.h" #include "src/snapshot/embedded/embedded-data.h" #include "src/snapshot/serializer-deserializer.h" #include "src/snapshot/snapshot.h" #include "src/strings/string-stream.h" #include "src/strings/unicode-decoder.h" #include "src/strings/unicode-inl.h" #include "src/tracing/trace-event.h" #include "src/utils/utils-inl.h" #include "src/utils/utils.h" // Has to be the last include (doesn't have include guards): #include "src/objects/object-macros.h" namespace v8 { namespace internal { #ifdef V8_ENABLE_THIRD_PARTY_HEAP Isolate* Heap::GetIsolateFromWritableObject(HeapObject object) { return reinterpret_cast<Isolate*>( third_party_heap::Heap::GetIsolate(object.address())); } #endif // These are outside the Heap class so they can be forward-declared // in heap-write-barrier-inl.h. bool Heap_PageFlagsAreConsistent(HeapObject object) { return Heap::PageFlagsAreConsistent(object); } void Heap_GenerationalBarrierSlow(HeapObject object, Address slot, HeapObject value) { Heap::GenerationalBarrierSlow(object, slot, value); } void Heap_MarkingBarrierSlow(HeapObject object, Address slot, HeapObject value) { Heap::MarkingBarrierSlow(object, slot, value); } void Heap_WriteBarrierForCodeSlow(Code host) { Heap::WriteBarrierForCodeSlow(host); } void Heap_MarkingBarrierForArrayBufferExtensionSlow( HeapObject object, ArrayBufferExtension* extension) { Heap::MarkingBarrierForArrayBufferExtensionSlow(object, extension); } void Heap_GenerationalBarrierForCodeSlow(Code host, RelocInfo* rinfo, HeapObject object) { Heap::GenerationalBarrierForCodeSlow(host, rinfo, object); } void Heap_MarkingBarrierForCodeSlow(Code host, RelocInfo* rinfo, HeapObject object) { Heap::MarkingBarrierForCodeSlow(host, rinfo, object); } void Heap_MarkingBarrierForDescriptorArraySlow(Heap* heap, HeapObject host, HeapObject descriptor_array, int number_of_own_descriptors) { Heap::MarkingBarrierForDescriptorArraySlow(heap, host, descriptor_array, number_of_own_descriptors); } void Heap_GenerationalEphemeronKeyBarrierSlow(Heap* heap, EphemeronHashTable table, Address slot) { heap->RecordEphemeronKeyWrite(table, slot); } void Heap::SetArgumentsAdaptorDeoptPCOffset(int pc_offset) { DCHECK_EQ(Smi::zero(), arguments_adaptor_deopt_pc_offset()); set_arguments_adaptor_deopt_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetConstructStubCreateDeoptPCOffset(int pc_offset) { DCHECK_EQ(Smi::zero(), construct_stub_create_deopt_pc_offset()); set_construct_stub_create_deopt_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetConstructStubInvokeDeoptPCOffset(int pc_offset) { DCHECK_EQ(Smi::zero(), construct_stub_invoke_deopt_pc_offset()); set_construct_stub_invoke_deopt_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetInterpreterEntryReturnPCOffset(int pc_offset) { DCHECK_EQ(Smi::zero(), interpreter_entry_return_pc_offset()); set_interpreter_entry_return_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetSerializedObjects(FixedArray objects) { DCHECK(isolate()->serializer_enabled()); set_serialized_objects(objects); } void Heap::SetSerializedGlobalProxySizes(FixedArray sizes) { DCHECK(isolate()->serializer_enabled()); set_serialized_global_proxy_sizes(sizes); } void Heap::SetBasicBlockProfilingData(Handle<ArrayList> list) { set_basic_block_profiling_data(*list); } bool Heap::GCCallbackTuple::operator==( const Heap::GCCallbackTuple& other) const { return other.callback == callback && other.data == data; } Heap::GCCallbackTuple& Heap::GCCallbackTuple::operator=( const Heap::GCCallbackTuple& other) V8_NOEXCEPT = default; struct Heap::StrongRootsList { FullObjectSlot start; FullObjectSlot end; StrongRootsList* next; }; class ScavengeTaskObserver : public AllocationObserver { public: ScavengeTaskObserver(Heap* heap, intptr_t step_size) : AllocationObserver(step_size), heap_(heap) {} void Step(int bytes_allocated, Address, size_t) override { heap_->ScheduleScavengeTaskIfNeeded(); } private: Heap* heap_; }; Heap::Heap() : isolate_(isolate()), memory_pressure_level_(MemoryPressureLevel::kNone), global_pretenuring_feedback_(kInitialFeedbackCapacity), safepoint_(new GlobalSafepoint(this)), external_string_table_(this), collection_barrier_(this) { // Ensure old_generation_size_ is a multiple of kPageSize. DCHECK_EQ(0, max_old_generation_size_ & (Page::kPageSize - 1)); set_native_contexts_list(Smi::zero()); set_allocation_sites_list(Smi::zero()); set_dirty_js_finalization_registries_list(Smi::zero()); set_dirty_js_finalization_registries_list_tail(Smi::zero()); // Put a dummy entry in the remembered pages so we can find the list the // minidump even if there are no real unmapped pages. RememberUnmappedPage(kNullAddress, false); } Heap::~Heap() = default; size_t Heap::MaxReserved() { const size_t kMaxNewLargeObjectSpaceSize = max_semi_space_size_; return static_cast<size_t>(2 * max_semi_space_size_ + kMaxNewLargeObjectSpaceSize + max_old_generation_size_); } size_t Heap::YoungGenerationSizeFromOldGenerationSize(size_t old_generation) { // Compute the semi space size and cap it. size_t ratio = old_generation <= kOldGenerationLowMemory ? kOldGenerationToSemiSpaceRatioLowMemory : kOldGenerationToSemiSpaceRatio; size_t semi_space = old_generation / ratio; semi_space = Min<size_t>(semi_space, kMaxSemiSpaceSize); semi_space = Max<size_t>(semi_space, kMinSemiSpaceSize); semi_space = RoundUp(semi_space, Page::kPageSize); return YoungGenerationSizeFromSemiSpaceSize(semi_space); } size_t Heap::HeapSizeFromPhysicalMemory(uint64_t physical_memory) { // Compute the old generation size and cap it. uint64_t old_generation = physical_memory / kPhysicalMemoryToOldGenerationRatio * kHeapLimitMultiplier; old_generation = Min<uint64_t>(old_generation, MaxOldGenerationSize(physical_memory)); old_generation = Max<uint64_t>(old_generation, V8HeapTrait::kMinSize); old_generation = RoundUp(old_generation, Page::kPageSize); size_t young_generation = YoungGenerationSizeFromOldGenerationSize( static_cast<size_t>(old_generation)); return static_cast<size_t>(old_generation) + young_generation; } void Heap::GenerationSizesFromHeapSize(size_t heap_size, size_t* young_generation_size, size_t* old_generation_size) { // Initialize values for the case when the given heap size is too small. *young_generation_size = 0; *old_generation_size = 0; // Binary search for the largest old generation size that fits to the given // heap limit considering the correspondingly sized young generation. size_t lower = 0, upper = heap_size; while (lower + 1 < upper) { size_t old_generation = lower + (upper - lower) / 2; size_t young_generation = YoungGenerationSizeFromOldGenerationSize(old_generation); if (old_generation + young_generation <= heap_size) { // This size configuration fits into the given heap limit. *young_generation_size = young_generation; *old_generation_size = old_generation; lower = old_generation; } else { upper = old_generation; } } } size_t Heap::MinYoungGenerationSize() { return YoungGenerationSizeFromSemiSpaceSize(kMinSemiSpaceSize); } size_t Heap::MinOldGenerationSize() { size_t paged_space_count = LAST_GROWABLE_PAGED_SPACE - FIRST_GROWABLE_PAGED_SPACE + 1; return paged_space_count * Page::kPageSize; } size_t Heap::AllocatorLimitOnMaxOldGenerationSize() { #ifdef V8_COMPRESS_POINTERS // Isolate and the young generation are also allocated on the heap. return kPtrComprHeapReservationSize - YoungGenerationSizeFromSemiSpaceSize(kMaxSemiSpaceSize) - RoundUp(sizeof(Isolate), size_t{1} << kPageSizeBits); #endif return std::numeric_limits<size_t>::max(); } size_t Heap::MaxOldGenerationSize(uint64_t physical_memory) { size_t max_size = V8HeapTrait::kMaxSize; // Finch experiment: Increase the heap size from 2GB to 4GB for 64-bit // systems with physical memory bigger than 16GB. The physical memory // is rounded up to GB. constexpr bool x64_bit = Heap::kHeapLimitMultiplier >= 2; if (FLAG_huge_max_old_generation_size && x64_bit && (physical_memory + 512 * MB) / GB >= 16) { DCHECK_EQ(max_size / GB, 2); max_size *= 2; } return Min(max_size, AllocatorLimitOnMaxOldGenerationSize()); } size_t Heap::YoungGenerationSizeFromSemiSpaceSize(size_t semi_space_size) { return semi_space_size * (2 + kNewLargeObjectSpaceToSemiSpaceRatio); } size_t Heap::SemiSpaceSizeFromYoungGenerationSize( size_t young_generation_size) { return young_generation_size / (2 + kNewLargeObjectSpaceToSemiSpaceRatio); } size_t Heap::Capacity() { if (!HasBeenSetUp()) return 0; return new_space_->Capacity() + OldGenerationCapacity(); } size_t Heap::OldGenerationCapacity() { if (!HasBeenSetUp()) return 0; PagedSpaceIterator spaces(this); size_t total = 0; for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { total += space->Capacity(); } return total + lo_space_->SizeOfObjects() + code_lo_space_->SizeOfObjects(); } size_t Heap::CommittedOldGenerationMemory() { if (!HasBeenSetUp()) return 0; PagedSpaceIterator spaces(this); size_t total = 0; for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { total += space->CommittedMemory(); } return total + lo_space_->Size() + code_lo_space_->Size(); } size_t Heap::CommittedMemoryOfUnmapper() { if (!HasBeenSetUp()) return 0; return memory_allocator()->unmapper()->CommittedBufferedMemory(); } size_t Heap::CommittedMemory() { if (!HasBeenSetUp()) return 0; return new_space_->CommittedMemory() + new_lo_space_->Size() + CommittedOldGenerationMemory(); } size_t Heap::CommittedPhysicalMemory() { if (!HasBeenSetUp()) return 0; size_t total = 0; for (SpaceIterator it(this); it.HasNext();) { total += it.Next()->CommittedPhysicalMemory(); } return total; } size_t Heap::CommittedMemoryExecutable() { if (!HasBeenSetUp()) return 0; return static_cast<size_t>(memory_allocator()->SizeExecutable()); } void Heap::UpdateMaximumCommitted() { if (!HasBeenSetUp()) return; const size_t current_committed_memory = CommittedMemory(); if (current_committed_memory > maximum_committed_) { maximum_committed_ = current_committed_memory; } } size_t Heap::Available() { if (!HasBeenSetUp()) return 0; size_t total = 0; for (SpaceIterator it(this); it.HasNext();) { total += it.Next()->Available(); } total += memory_allocator()->Available(); return total; } bool Heap::CanExpandOldGeneration(size_t size) { if (force_oom_) return false; if (OldGenerationCapacity() + size > max_old_generation_size_) return false; // The OldGenerationCapacity does not account compaction spaces used // during evacuation. Ensure that expanding the old generation does push // the total allocated memory size over the maximum heap size. return memory_allocator()->Size() + size <= MaxReserved(); } bool Heap::CanExpandOldGenerationBackground(size_t size) { if (force_oom_) return false; return memory_allocator()->Size() + size <= MaxReserved(); } bool Heap::HasBeenSetUp() const { // We will always have a new space when the heap is set up. return new_space_ != nullptr; } GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space, const char** reason) { // Is global GC requested? if (space != NEW_SPACE && space != NEW_LO_SPACE) { isolate_->counters()->gc_compactor_caused_by_request()->Increment(); *reason = "GC in old space requested"; return MARK_COMPACTOR; } if (FLAG_gc_global || (FLAG_stress_compaction && (gc_count_ & 1) != 0)) { *reason = "GC in old space forced by flags"; return MARK_COMPACTOR; } if (incremental_marking()->NeedsFinalization() && AllocationLimitOvershotByLargeMargin()) { *reason = "Incremental marking needs finalization"; return MARK_COMPACTOR; } // Over-estimate the new space size using capacity to allow some slack. if (!CanExpandOldGeneration(new_space_->TotalCapacity() + new_lo_space()->Size())) { isolate_->counters() ->gc_compactor_caused_by_oldspace_exhaustion() ->Increment(); *reason = "scavenge might not succeed"; return MARK_COMPACTOR; } // Default *reason = nullptr; return YoungGenerationCollector(); } void Heap::SetGCState(HeapState state) { gc_state_ = state; } void Heap::PrintShortHeapStatistics() { if (!FLAG_trace_gc_verbose) return; PrintIsolate(isolate_, "Memory allocator, used: %6zu KB," " available: %6zu KB\n", memory_allocator()->Size() / KB, memory_allocator()->Available() / KB); PrintIsolate(isolate_, "Read-only space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", read_only_space_->Size() / KB, size_t{0}, read_only_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "New space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", new_space_->Size() / KB, new_space_->Available() / KB, new_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "New large object space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", new_lo_space_->SizeOfObjects() / KB, new_lo_space_->Available() / KB, new_lo_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Old space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", old_space_->SizeOfObjects() / KB, old_space_->Available() / KB, old_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Code space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", code_space_->SizeOfObjects() / KB, code_space_->Available() / KB, code_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Map space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", map_space_->SizeOfObjects() / KB, map_space_->Available() / KB, map_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Large object space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", lo_space_->SizeOfObjects() / KB, lo_space_->Available() / KB, lo_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Code large object space, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", code_lo_space_->SizeOfObjects() / KB, code_lo_space_->Available() / KB, code_lo_space_->CommittedMemory() / KB); ReadOnlySpace* const ro_space = read_only_space_; PrintIsolate(isolate_, "All spaces, used: %6zu KB" ", available: %6zu KB" ", committed: %6zu KB\n", (this->SizeOfObjects() + ro_space->Size()) / KB, (this->Available()) / KB, (this->CommittedMemory() + ro_space->CommittedMemory()) / KB); PrintIsolate(isolate_, "Unmapper buffering %zu chunks of committed: %6zu KB\n", memory_allocator()->unmapper()->NumberOfCommittedChunks(), CommittedMemoryOfUnmapper() / KB); PrintIsolate(isolate_, "External memory reported: %6" PRId64 " KB\n", isolate()->isolate_data()->external_memory_ / KB); PrintIsolate(isolate_, "Backing store memory: %6zu KB\n", backing_store_bytes_ / KB); PrintIsolate(isolate_, "External memory global %zu KB\n", external_memory_callback_() / KB); PrintIsolate(isolate_, "Total time spent in GC : %.1f ms\n", total_gc_time_ms_); } void Heap::PrintFreeListsStats() { DCHECK(FLAG_trace_gc_freelists); if (FLAG_trace_gc_freelists_verbose) { PrintIsolate(isolate_, "Freelists statistics per Page: " "[category: length || total free bytes]\n"); } std::vector<int> categories_lengths( old_space()->free_list()->number_of_categories(), 0); std::vector<size_t> categories_sums( old_space()->free_list()->number_of_categories(), 0); unsigned int pageCnt = 0; // This loops computes freelists lengths and sum. // If FLAG_trace_gc_freelists_verbose is enabled, it also prints // the stats of each FreeListCategory of each Page. for (Page* page : *old_space()) { std::ostringstream out_str; if (FLAG_trace_gc_freelists_verbose) { out_str << "Page " << std::setw(4) << pageCnt; } for (int cat = kFirstCategory; cat <= old_space()->free_list()->last_category(); cat++) { FreeListCategory* free_list = page->free_list_category(static_cast<FreeListCategoryType>(cat)); int length = free_list->FreeListLength(); size_t sum = free_list->SumFreeList(); if (FLAG_trace_gc_freelists_verbose) { out_str << "[" << cat << ": " << std::setw(4) << length << " || " << std::setw(6) << sum << " ]" << (cat == old_space()->free_list()->last_category() ? "\n" : ", "); } categories_lengths[cat] += length; categories_sums[cat] += sum; } if (FLAG_trace_gc_freelists_verbose) { PrintIsolate(isolate_, "%s", out_str.str().c_str()); } pageCnt++; } // Print statistics about old_space (pages, free/wasted/used memory...). PrintIsolate( isolate_, "%d pages. Free space: %.1f MB (waste: %.2f). " "Usage: %.1f/%.1f (MB) -> %.2f%%.\n", pageCnt, static_cast<double>(old_space_->Available()) / MB, static_cast<double>(old_space_->Waste()) / MB, static_cast<double>(old_space_->Size()) / MB, static_cast<double>(old_space_->Capacity()) / MB, static_cast<double>(old_space_->Size()) / old_space_->Capacity() * 100); // Print global statistics of each FreeListCategory (length & sum). PrintIsolate(isolate_, "FreeLists global statistics: " "[category: length || total free KB]\n"); std::ostringstream out_str; for (int cat = kFirstCategory; cat <= old_space()->free_list()->last_category(); cat++) { out_str << "[" << cat << ": " << categories_lengths[cat] << " || " << std::fixed << std::setprecision(2) << static_cast<double>(categories_sums[cat]) / KB << " KB]" << (cat == old_space()->free_list()->last_category() ? "\n" : ", "); } PrintIsolate(isolate_, "%s", out_str.str().c_str()); } void Heap::DumpJSONHeapStatistics(std::stringstream& stream) { HeapStatistics stats; reinterpret_cast<v8::Isolate*>(isolate())->GetHeapStatistics(&stats); // clang-format off #define DICT(s) "{" << s << "}" #define LIST(s) "[" << s << "]" #define ESCAPE(s) "\"" << s << "\"" #define MEMBER(s) ESCAPE(s) << ":" auto SpaceStatistics = [this](int space_index) { HeapSpaceStatistics space_stats; reinterpret_cast<v8::Isolate*>(isolate())->GetHeapSpaceStatistics( &space_stats, space_index); std::stringstream stream; stream << DICT( MEMBER("name") << ESCAPE(BaseSpace::GetSpaceName( static_cast<AllocationSpace>(space_index))) << "," MEMBER("size") << space_stats.space_size() << "," MEMBER("used_size") << space_stats.space_used_size() << "," MEMBER("available_size") << space_stats.space_available_size() << "," MEMBER("physical_size") << space_stats.physical_space_size()); return stream.str(); }; stream << DICT( MEMBER("isolate") << ESCAPE(reinterpret_cast<void*>(isolate())) << "," MEMBER("id") << gc_count() << "," MEMBER("time_ms") << isolate()->time_millis_since_init() << "," MEMBER("total_heap_size") << stats.total_heap_size() << "," MEMBER("total_heap_size_executable") << stats.total_heap_size_executable() << "," MEMBER("total_physical_size") << stats.total_physical_size() << "," MEMBER("total_available_size") << stats.total_available_size() << "," MEMBER("used_heap_size") << stats.used_heap_size() << "," MEMBER("heap_size_limit") << stats.heap_size_limit() << "," MEMBER("malloced_memory") << stats.malloced_memory() << "," MEMBER("external_memory") << stats.external_memory() << "," MEMBER("peak_malloced_memory") << stats.peak_malloced_memory() << "," MEMBER("spaces") << LIST( SpaceStatistics(RO_SPACE) << "," << SpaceStatistics(NEW_SPACE) << "," << SpaceStatistics(OLD_SPACE) << "," << SpaceStatistics(CODE_SPACE) << "," << SpaceStatistics(MAP_SPACE) << "," << SpaceStatistics(LO_SPACE) << "," << SpaceStatistics(CODE_LO_SPACE) << "," << SpaceStatistics(NEW_LO_SPACE))); #undef DICT #undef LIST #undef ESCAPE #undef MEMBER // clang-format on } void Heap::ReportStatisticsAfterGC() { for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount); ++i) { int count = deferred_counters_[i]; deferred_counters_[i] = 0; while (count > 0) { count--; isolate()->CountUsage(static_cast<v8::Isolate::UseCounterFeature>(i)); } } } void Heap::AddHeapObjectAllocationTracker( HeapObjectAllocationTracker* tracker) { if (allocation_trackers_.empty() && FLAG_inline_new) { DisableInlineAllocation(); } allocation_trackers_.push_back(tracker); } void Heap::RemoveHeapObjectAllocationTracker( HeapObjectAllocationTracker* tracker) { allocation_trackers_.erase(std::remove(allocation_trackers_.begin(), allocation_trackers_.end(), tracker), allocation_trackers_.end()); if (allocation_trackers_.empty() && FLAG_inline_new) { EnableInlineAllocation(); } } void Heap::AddRetainingPathTarget(Handle<HeapObject> object, RetainingPathOption option) { if (!FLAG_track_retaining_path) { PrintF("Retaining path tracking requires --track-retaining-path\n"); } else { Handle<WeakArrayList> array(retaining_path_targets(), isolate()); int index = array->length(); array = WeakArrayList::AddToEnd(isolate(), array, MaybeObjectHandle::Weak(object)); set_retaining_path_targets(*array); DCHECK_EQ(array->length(), index + 1); retaining_path_target_option_[index] = option; } } bool Heap::IsRetainingPathTarget(HeapObject object, RetainingPathOption* option) { WeakArrayList targets = retaining_path_targets(); int length = targets.length(); MaybeObject object_to_check = HeapObjectReference::Weak(object); for (int i = 0; i < length; i++) { MaybeObject target = targets.Get(i); DCHECK(target->IsWeakOrCleared()); if (target == object_to_check) { DCHECK(retaining_path_target_option_.count(i)); *option = retaining_path_target_option_[i]; return true; } } return false; } void Heap::PrintRetainingPath(HeapObject target, RetainingPathOption option) { PrintF("\n\n\n"); PrintF("#################################################\n"); PrintF("Retaining path for %p:\n", reinterpret_cast<void*>(target.ptr())); HeapObject object = target; std::vector<std::pair<HeapObject, bool>> retaining_path; Root root = Root::kUnknown; bool ephemeron = false; while (true) { retaining_path.push_back(std::make_pair(object, ephemeron)); if (option == RetainingPathOption::kTrackEphemeronPath && ephemeron_retainer_.count(object)) { object = ephemeron_retainer_[object]; ephemeron = true; } else if (retainer_.count(object)) { object = retainer_[object]; ephemeron = false; } else { if (retaining_root_.count(object)) { root = retaining_root_[object]; } break; } } int distance = static_cast<int>(retaining_path.size()); for (auto node : retaining_path) { HeapObject object = node.first; bool ephemeron = node.second; PrintF("\n"); PrintF("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n"); PrintF("Distance from root %d%s: ", distance, ephemeron ? " (ephemeron)" : ""); object.ShortPrint(); PrintF("\n"); #ifdef OBJECT_PRINT object.Print(); PrintF("\n"); #endif --distance; } PrintF("\n"); PrintF("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n"); PrintF("Root: %s\n", RootVisitor::RootName(root)); PrintF("-------------------------------------------------\n"); } void Heap::AddRetainer(HeapObject retainer, HeapObject object) { if (retainer_.count(object)) return; retainer_[object] = retainer; RetainingPathOption option = RetainingPathOption::kDefault; if (IsRetainingPathTarget(object, &option)) { // Check if the retaining path was already printed in // AddEphemeronRetainer(). if (ephemeron_retainer_.count(object) == 0 || option == RetainingPathOption::kDefault) { PrintRetainingPath(object, option); } } } void Heap::AddEphemeronRetainer(HeapObject retainer, HeapObject object) { if (ephemeron_retainer_.count(object)) return; ephemeron_retainer_[object] = retainer; RetainingPathOption option = RetainingPathOption::kDefault; if (IsRetainingPathTarget(object, &option) && option == RetainingPathOption::kTrackEphemeronPath) { // Check if the retaining path was already printed in AddRetainer(). if (retainer_.count(object) == 0) { PrintRetainingPath(object, option); } } } void Heap::AddRetainingRoot(Root root, HeapObject object) { if (retaining_root_.count(object)) return; retaining_root_[object] = root; RetainingPathOption option = RetainingPathOption::kDefault; if (IsRetainingPathTarget(object, &option)) { PrintRetainingPath(object, option); } } void Heap::IncrementDeferredCount(v8::Isolate::UseCounterFeature feature) { deferred_counters_[feature]++; } bool Heap::UncommitFromSpace() { return new_space_->UncommitFromSpace(); } void Heap::GarbageCollectionPrologue() { TRACE_GC(tracer(), GCTracer::Scope::HEAP_PROLOGUE); { AllowHeapAllocation for_the_first_part_of_prologue; gc_count_++; } // Reset GC statistics. promoted_objects_size_ = 0; previous_semi_space_copied_object_size_ = semi_space_copied_object_size_; semi_space_copied_object_size_ = 0; nodes_died_in_new_space_ = 0; nodes_copied_in_new_space_ = 0; nodes_promoted_ = 0; UpdateMaximumCommitted(); #ifdef DEBUG DCHECK(!AllowHeapAllocation::IsAllowed() && gc_state_ == NOT_IN_GC); if (FLAG_gc_verbose) Print(); #endif // DEBUG if (new_space_->IsAtMaximumCapacity()) { maximum_size_scavenges_++; } else { maximum_size_scavenges_ = 0; } if (FLAG_track_retaining_path) { retainer_.clear(); ephemeron_retainer_.clear(); retaining_root_.clear(); } memory_allocator()->unmapper()->PrepareForGC(); } void Heap::GarbageCollectionPrologueInSafepoint() { UpdateNewSpaceAllocationCounter(); CheckNewSpaceExpansionCriteria(); } size_t Heap::SizeOfObjects() { size_t total = 0; for (SpaceIterator it(this); it.HasNext();) { total += it.Next()->SizeOfObjects(); } return total; } size_t Heap::TotalGlobalHandlesSize() { return isolate_->global_handles()->TotalSize(); } size_t Heap::UsedGlobalHandlesSize() { return isolate_->global_handles()->UsedSize(); } void Heap::MergeAllocationSitePretenuringFeedback( const PretenuringFeedbackMap& local_pretenuring_feedback) { AllocationSite site; for (auto& site_and_count : local_pretenuring_feedback) { site = site_and_count.first; MapWord map_word = site_and_count.first.map_word(); if (map_word.IsForwardingAddress()) { site = AllocationSite::cast(map_word.ToForwardingAddress()); } // We have not validated the allocation site yet, since we have not // dereferenced the site during collecting information. // This is an inlined check of AllocationMemento::IsValid. if (!site.IsAllocationSite() || site.IsZombie()) continue; const int value = static_cast<int>(site_and_count.second); DCHECK_LT(0, value); if (site.IncrementMementoFoundCount(value)) { // For sites in the global map the count is accessed through the site. global_pretenuring_feedback_.insert(std::make_pair(site, 0)); } } } void Heap::AddAllocationObserversToAllSpaces( AllocationObserver* observer, AllocationObserver* new_space_observer) { DCHECK(observer && new_space_observer); for (SpaceIterator it(this); it.HasNext();) { Space* space = it.Next(); if (space == new_space()) { space->AddAllocationObserver(new_space_observer); } else { space->AddAllocationObserver(observer); } } } void Heap::RemoveAllocationObserversFromAllSpaces( AllocationObserver* observer, AllocationObserver* new_space_observer) { DCHECK(observer && new_space_observer); for (SpaceIterator it(this); it.HasNext();) { Space* space = it.Next(); if (space == new_space()) { space->RemoveAllocationObserver(new_space_observer); } else { space->RemoveAllocationObserver(observer); } } } namespace { inline bool MakePretenureDecision( AllocationSite site, AllocationSite::PretenureDecision current_decision, double ratio, bool maximum_size_scavenge) { // Here we just allow state transitions from undecided or maybe tenure // to don't tenure, maybe tenure, or tenure. if ((current_decision == AllocationSite::kUndecided || current_decision == AllocationSite::kMaybeTenure)) { if (ratio >= AllocationSite::kPretenureRatio) { // We just transition into tenure state when the semi-space was at // maximum capacity. if (maximum_size_scavenge) { site.set_deopt_dependent_code(true); site.set_pretenure_decision(AllocationSite::kTenure); // Currently we just need to deopt when we make a state transition to // tenure. return true; } site.set_pretenure_decision(AllocationSite::kMaybeTenure); } else { site.set_pretenure_decision(AllocationSite::kDontTenure); } } return false; } inline bool DigestPretenuringFeedback(Isolate* isolate, AllocationSite site, bool maximum_size_scavenge) { bool deopt = false; int create_count = site.memento_create_count(); int found_count = site.memento_found_count(); bool minimum_mementos_created = create_count >= AllocationSite::kPretenureMinimumCreated; double ratio = minimum_mementos_created || FLAG_trace_pretenuring_statistics ? static_cast<double>(found_count) / create_count : 0.0; AllocationSite::PretenureDecision current_decision = site.pretenure_decision(); if (minimum_mementos_created) { deopt = MakePretenureDecision(site, current_decision, ratio, maximum_size_scavenge); } if (FLAG_trace_pretenuring_statistics) { PrintIsolate(isolate, "pretenuring: AllocationSite(%p): (created, found, ratio) " "(%d, %d, %f) %s => %s\n", reinterpret_cast<void*>(site.ptr()), create_count, found_count, ratio, site.PretenureDecisionName(current_decision), site.PretenureDecisionName(site.pretenure_decision())); } // Clear feedback calculation fields until the next gc. site.set_memento_found_count(0); site.set_memento_create_count(0); return deopt; } } // namespace void Heap::RemoveAllocationSitePretenuringFeedback(AllocationSite site) { global_pretenuring_feedback_.erase(site); } bool Heap::DeoptMaybeTenuredAllocationSites() { return new_space_->IsAtMaximumCapacity() && maximum_size_scavenges_ == 0; } void Heap::ProcessPretenuringFeedback() { bool trigger_deoptimization = false; if (FLAG_allocation_site_pretenuring) { int tenure_decisions = 0; int dont_tenure_decisions = 0; int allocation_mementos_found = 0; int allocation_sites = 0; int active_allocation_sites = 0; AllocationSite site; // Step 1: Digest feedback for recorded allocation sites. bool maximum_size_scavenge = MaximumSizeScavenge(); for (auto& site_and_count : global_pretenuring_feedback_) { allocation_sites++; site = site_and_count.first; // Count is always access through the site. DCHECK_EQ(0, site_and_count.second); int found_count = site.memento_found_count(); // An entry in the storage does not imply that the count is > 0 because // allocation sites might have been reset due to too many objects dying // in old space. if (found_count > 0) { DCHECK(site.IsAllocationSite()); active_allocation_sites++; allocation_mementos_found += found_count; if (DigestPretenuringFeedback(isolate_, site, maximum_size_scavenge)) { trigger_deoptimization = true; } if (site.GetAllocationType() == AllocationType::kOld) { tenure_decisions++; } else { dont_tenure_decisions++; } } } // Step 2: Deopt maybe tenured allocation sites if necessary. bool deopt_maybe_tenured = DeoptMaybeTenuredAllocationSites(); if (deopt_maybe_tenured) { ForeachAllocationSite( allocation_sites_list(), [&allocation_sites, &trigger_deoptimization](AllocationSite site) { DCHECK(site.IsAllocationSite()); allocation_sites++; if (site.IsMaybeTenure()) { site.set_deopt_dependent_code(true); trigger_deoptimization = true; } }); } if (trigger_deoptimization) { isolate_->stack_guard()->RequestDeoptMarkedAllocationSites(); } if (FLAG_trace_pretenuring_statistics && (allocation_mementos_found > 0 || tenure_decisions > 0 || dont_tenure_decisions > 0)) { PrintIsolate(isolate(), "pretenuring: deopt_maybe_tenured=%d visited_sites=%d " "active_sites=%d " "mementos=%d tenured=%d not_tenured=%d\n", deopt_maybe_tenured ? 1 : 0, allocation_sites, active_allocation_sites, allocation_mementos_found, tenure_decisions, dont_tenure_decisions); } global_pretenuring_feedback_.clear(); global_pretenuring_feedback_.reserve(kInitialFeedbackCapacity); } } void Heap::InvalidateCodeDeoptimizationData(Code code) { CodePageMemoryModificationScope modification_scope(code); code.set_deoptimization_data(ReadOnlyRoots(this).empty_fixed_array()); } void Heap::DeoptMarkedAllocationSites() { // TODO(hpayer): If iterating over the allocation sites list becomes a // performance issue, use a cache data structure in heap instead. ForeachAllocationSite(allocation_sites_list(), [](AllocationSite site) { if (site.deopt_dependent_code()) { site.dependent_code().MarkCodeForDeoptimization( DependentCode::kAllocationSiteTenuringChangedGroup); site.set_deopt_dependent_code(false); } }); Deoptimizer::DeoptimizeMarkedCode(isolate_); } void Heap::GarbageCollectionEpilogueInSafepoint() { #define UPDATE_COUNTERS_FOR_SPACE(space) \ isolate_->counters()->space##_bytes_available()->Set( \ static_cast<int>(space()->Available())); \ isolate_->counters()->space##_bytes_committed()->Set( \ static_cast<int>(space()->CommittedMemory())); \ isolate_->counters()->space##_bytes_used()->Set( \ static_cast<int>(space()->SizeOfObjects())); #define UPDATE_FRAGMENTATION_FOR_SPACE(space) \ if (space()->CommittedMemory() > 0) { \ isolate_->counters()->external_fragmentation_##space()->AddSample( \ static_cast<int>(100 - (space()->SizeOfObjects() * 100.0) / \ space()->CommittedMemory())); \ } #define UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(space) \ UPDATE_COUNTERS_FOR_SPACE(space) \ UPDATE_FRAGMENTATION_FOR_SPACE(space) UPDATE_COUNTERS_FOR_SPACE(new_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(old_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(code_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(map_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(lo_space) #undef UPDATE_COUNTERS_FOR_SPACE #undef UPDATE_FRAGMENTATION_FOR_SPACE #undef UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE #ifdef DEBUG // Old-to-new slot sets must be empty after each collection. for (SpaceIterator it(this); it.HasNext();) { Space* space = it.Next(); for (MemoryChunk* chunk = space->first_page(); chunk != space->last_page(); chunk = chunk->list_node().next()) DCHECK_NULL(chunk->invalidated_slots<OLD_TO_NEW>()); } if (FLAG_print_global_handles) isolate_->global_handles()->Print(); if (FLAG_print_handles) PrintHandles(); if (FLAG_gc_verbose) Print(); if (FLAG_code_stats) ReportCodeStatistics("After GC"); if (FLAG_check_handle_count) CheckHandleCount(); #endif } void Heap::GarbageCollectionEpilogue() { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE); if (Heap::ShouldZapGarbage() || FLAG_clear_free_memory) { ZapFromSpace(); } AllowHeapAllocation for_the_rest_of_the_epilogue; UpdateMaximumCommitted(); isolate_->counters()->alive_after_last_gc()->Set( static_cast<int>(SizeOfObjects())); isolate_->counters()->string_table_capacity()->Set(string_table().Capacity()); isolate_->counters()->number_of_symbols()->Set( string_table().NumberOfElements()); if (CommittedMemory() > 0) { isolate_->counters()->external_fragmentation_total()->AddSample( static_cast<int>(100 - (SizeOfObjects() * 100.0) / CommittedMemory())); isolate_->counters()->heap_sample_total_committed()->AddSample( static_cast<int>(CommittedMemory() / KB)); isolate_->counters()->heap_sample_total_used()->AddSample( static_cast<int>(SizeOfObjects() / KB)); isolate_->counters()->heap_sample_map_space_committed()->AddSample( static_cast<int>(map_space()->CommittedMemory() / KB)); isolate_->counters()->heap_sample_code_space_committed()->AddSample( static_cast<int>(code_space()->CommittedMemory() / KB)); isolate_->counters()->heap_sample_maximum_committed()->AddSample( static_cast<int>(MaximumCommittedMemory() / KB)); } #ifdef DEBUG ReportStatisticsAfterGC(); #endif // DEBUG last_gc_time_ = MonotonicallyIncreasingTimeInMs(); { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE_REDUCE_NEW_SPACE); ReduceNewSpaceSize(); } } class GCCallbacksScope { public: explicit GCCallbacksScope(Heap* heap) : heap_(heap) { heap_->gc_callbacks_depth_++; } ~GCCallbacksScope() { heap_->gc_callbacks_depth_--; } bool CheckReenter() { return heap_->gc_callbacks_depth_ == 1; } private: Heap* heap_; }; void Heap::HandleGCRequest() { if (FLAG_stress_scavenge > 0 && stress_scavenge_observer_->HasRequestedGC()) { CollectAllGarbage(NEW_SPACE, GarbageCollectionReason::kTesting); stress_scavenge_observer_->RequestedGCDone(); } else if (HighMemoryPressure()) { incremental_marking()->reset_request_type(); CheckMemoryPressure(); } else if (incremental_marking()->request_type() == IncrementalMarking::COMPLETE_MARKING) { incremental_marking()->reset_request_type(); CollectAllGarbage(current_gc_flags_, GarbageCollectionReason::kFinalizeMarkingViaStackGuard, current_gc_callback_flags_); } else if (incremental_marking()->request_type() == IncrementalMarking::FINALIZATION && incremental_marking()->IsMarking() && !incremental_marking()->finalize_marking_completed()) { incremental_marking()->reset_request_type(); FinalizeIncrementalMarkingIncrementally( GarbageCollectionReason::kFinalizeMarkingViaStackGuard); } } void Heap::ScheduleScavengeTaskIfNeeded() { DCHECK_NOT_NULL(scavenge_job_); scavenge_job_->ScheduleTaskIfNeeded(this); } TimedHistogram* Heap::GCTypePriorityTimer(GarbageCollector collector) { if (IsYoungGenerationCollector(collector)) { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_scavenger_background(); } return isolate_->counters()->gc_scavenger_foreground(); } else { if (!incremental_marking()->IsStopped()) { if (ShouldReduceMemory()) { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_finalize_reduce_memory_background(); } return isolate_->counters()->gc_finalize_reduce_memory_foreground(); } else { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_finalize_background(); } return isolate_->counters()->gc_finalize_foreground(); } } else { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_compactor_background(); } return isolate_->counters()->gc_compactor_foreground(); } } } TimedHistogram* Heap::GCTypeTimer(GarbageCollector collector) { if (IsYoungGenerationCollector(collector)) { return isolate_->counters()->gc_scavenger(); } if (incremental_marking()->IsStopped()) { return isolate_->counters()->gc_compactor(); } if (ShouldReduceMemory()) { return isolate_->counters()->gc_finalize_reduce_memory(); } if (incremental_marking()->IsMarking() && incremental_marking()->marking_worklists()->IsPerContextMode()) { return isolate_->counters()->gc_finalize_measure_memory(); } return isolate_->counters()->gc_finalize(); } void Heap::CollectAllGarbage(int flags, GarbageCollectionReason gc_reason, const v8::GCCallbackFlags gc_callback_flags) { // Since we are ignoring the return value, the exact choice of space does // not matter, so long as we do not specify NEW_SPACE, which would not // cause a full GC. set_current_gc_flags(flags); CollectGarbage(OLD_SPACE, gc_reason, gc_callback_flags); set_current_gc_flags(kNoGCFlags); } namespace { intptr_t CompareWords(int size, HeapObject a, HeapObject b) { int slots = size / kTaggedSize; DCHECK_EQ(a.Size(), size); DCHECK_EQ(b.Size(), size); Tagged_t* slot_a = reinterpret_cast<Tagged_t*>(a.address()); Tagged_t* slot_b = reinterpret_cast<Tagged_t*>(b.address()); for (int i = 0; i < slots; i++) { if (*slot_a != *slot_b) { return *slot_a - *slot_b; } slot_a++; slot_b++; } return 0; } void ReportDuplicates(int size, std::vector<HeapObject>* objects) { if (objects->size() == 0) return; sort(objects->begin(), objects->end(), [size](HeapObject a, HeapObject b) { intptr_t c = CompareWords(size, a, b); if (c != 0) return c < 0; return a < b; }); std::vector<std::pair<int, HeapObject>> duplicates; HeapObject current = (*objects)[0]; int count = 1; for (size_t i = 1; i < objects->size(); i++) { if (CompareWords(size, current, (*objects)[i]) == 0) { count++; } else { if (count > 1) { duplicates.push_back(std::make_pair(count - 1, current)); } count = 1; current = (*objects)[i]; } } if (count > 1) { duplicates.push_back(std::make_pair(count - 1, current)); } int threshold = FLAG_trace_duplicate_threshold_kb * KB; sort(duplicates.begin(), duplicates.end()); for (auto it = duplicates.rbegin(); it != duplicates.rend(); ++it) { int duplicate_bytes = it->first * size; if (duplicate_bytes < threshold) break; PrintF("%d duplicates of size %d each (%dKB)\n", it->first, size, duplicate_bytes / KB); PrintF("Sample object: "); it->second.Print(); PrintF("============================\n"); } } } // anonymous namespace void Heap::CollectAllAvailableGarbage(GarbageCollectionReason gc_reason) { // Since we are ignoring the return value, the exact choice of space does // not matter, so long as we do not specify NEW_SPACE, which would not // cause a full GC. // Major GC would invoke weak handle callbacks on weakly reachable // handles, but won't collect weakly reachable objects until next // major GC. Therefore if we collect aggressively and weak handle callback // has been invoked, we rerun major GC to release objects which become // garbage. // Note: as weak callbacks can execute arbitrary code, we cannot // hope that eventually there will be no weak callbacks invocations. // Therefore stop recollecting after several attempts. if (gc_reason == GarbageCollectionReason::kLastResort) { InvokeNearHeapLimitCallback(); } RuntimeCallTimerScope runtime_timer( isolate(), RuntimeCallCounterId::kGC_Custom_AllAvailableGarbage); // The optimizing compiler may be unnecessarily holding on to memory. isolate()->AbortConcurrentOptimization(BlockingBehavior::kDontBlock); isolate()->ClearSerializerData(); set_current_gc_flags( kReduceMemoryFootprintMask | (gc_reason == GarbageCollectionReason::kLowMemoryNotification ? kForcedGC : 0)); isolate_->compilation_cache()->Clear(); const int kMaxNumberOfAttempts = 7; const int kMinNumberOfAttempts = 2; for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) { if (!CollectGarbage(OLD_SPACE, gc_reason, kNoGCCallbackFlags) && attempt + 1 >= kMinNumberOfAttempts) { break; } } set_current_gc_flags(kNoGCFlags); new_space_->Shrink(); new_lo_space_->SetCapacity(new_space_->Capacity() * kNewLargeObjectSpaceToSemiSpaceRatio); UncommitFromSpace(); EagerlyFreeExternalMemory(); if (FLAG_trace_duplicate_threshold_kb) { std::map<int, std::vector<HeapObject>> objects_by_size; PagedSpaceIterator spaces(this); for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { PagedSpaceObjectIterator it(this, space); for (HeapObject obj = it.Next(); !obj.is_null(); obj = it.Next()) { objects_by_size[obj.Size()].push_back(obj); } } { LargeObjectSpaceObjectIterator it(lo_space()); for (HeapObject obj = it.Next(); !obj.is_null(); obj = it.Next()) { objects_by_size[obj.Size()].push_back(obj); } } for (auto it = objects_by_size.rbegin(); it != objects_by_size.rend(); ++it) { ReportDuplicates(it->first, &it->second); } } } void Heap::PreciseCollectAllGarbage(int flags, GarbageCollectionReason gc_reason, const GCCallbackFlags gc_callback_flags) { if (!incremental_marking()->IsStopped()) { FinalizeIncrementalMarkingAtomically(gc_reason); } CollectAllGarbage(flags, gc_reason, gc_callback_flags); } void Heap::ReportExternalMemoryPressure() { const GCCallbackFlags kGCCallbackFlagsForExternalMemory = static_cast<GCCallbackFlags>( kGCCallbackFlagSynchronousPhantomCallbackProcessing | kGCCallbackFlagCollectAllExternalMemory); int64_t current = isolate()->isolate_data()->external_memory_; int64_t baseline = isolate()->isolate_data()->external_memory_low_since_mark_compact_; int64_t limit = isolate()->isolate_data()->external_memory_limit_; TRACE_EVENT2( "devtools.timeline,v8", "V8.ExternalMemoryPressure", "external_memory_mb", static_cast<int>((current - baseline) / MB), "external_memory_limit_mb", static_cast<int>((limit - baseline) / MB)); if (current > baseline + external_memory_hard_limit()) { CollectAllGarbage( kReduceMemoryFootprintMask, GarbageCollectionReason::kExternalMemoryPressure, static_cast<GCCallbackFlags>(kGCCallbackFlagCollectAllAvailableGarbage | kGCCallbackFlagsForExternalMemory)); return; } if (incremental_marking()->IsStopped()) { if (incremental_marking()->CanBeActivated()) { StartIncrementalMarking(GCFlagsForIncrementalMarking(), GarbageCollectionReason::kExternalMemoryPressure, kGCCallbackFlagsForExternalMemory); } else { CollectAllGarbage(i::Heap::kNoGCFlags, GarbageCollectionReason::kExternalMemoryPressure, kGCCallbackFlagsForExternalMemory); } } else { // Incremental marking is turned on an has already been started. const double kMinStepSize = 5; const double kMaxStepSize = 10; const double ms_step = Min( kMaxStepSize, Max(kMinStepSize, static_cast<double>(current) / limit * kMinStepSize)); const double deadline = MonotonicallyIncreasingTimeInMs() + ms_step; // Extend the gc callback flags with external memory flags. current_gc_callback_flags_ = static_cast<GCCallbackFlags>( current_gc_callback_flags_ | kGCCallbackFlagsForExternalMemory); incremental_marking()->AdvanceWithDeadline( deadline, IncrementalMarking::GC_VIA_STACK_GUARD, StepOrigin::kV8); } } void Heap::EnsureFillerObjectAtTop() { // There may be an allocation memento behind objects in new space. Upon // evacuation of a non-full new space (or if we are on the last page) there // may be uninitialized memory behind top. We fill the remainder of the page // with a filler. Address to_top = new_space_->top(); Page* page = Page::FromAddress(to_top - kTaggedSize); if (page->Contains(to_top)) { int remaining_in_page = static_cast<int>(page->area_end() - to_top); CreateFillerObjectAt(to_top, remaining_in_page, ClearRecordedSlots::kNo); } } Heap::DevToolsTraceEventScope::DevToolsTraceEventScope(Heap* heap, const char* event_name, const char* event_type) : heap_(heap), event_name_(event_name) { TRACE_EVENT_BEGIN2("devtools.timeline,v8", event_name_, "usedHeapSizeBefore", heap_->SizeOfObjects(), "type", event_type); } Heap::DevToolsTraceEventScope::~DevToolsTraceEventScope() { TRACE_EVENT_END1("devtools.timeline,v8", event_name_, "usedHeapSizeAfter", heap_->SizeOfObjects()); } bool Heap::CollectGarbage(AllocationSpace space, GarbageCollectionReason gc_reason, const v8::GCCallbackFlags gc_callback_flags) { const char* collector_reason = nullptr; GarbageCollector collector = SelectGarbageCollector(space, &collector_reason); is_current_gc_forced_ = gc_callback_flags & v8::kGCCallbackFlagForced || current_gc_flags_ & kForcedGC; DevToolsTraceEventScope devtools_trace_event_scope( this, IsYoungGenerationCollector(collector) ? "MinorGC" : "MajorGC", GarbageCollectionReasonToString(gc_reason)); if (!CanExpandOldGeneration(new_space()->Capacity() + new_lo_space()->Size())) { InvokeNearHeapLimitCallback(); } // Filter on-stack reference below this method. isolate() ->global_handles() ->CleanupOnStackReferencesBelowCurrentStackPosition(); // Ensure that all pending phantom callbacks are invoked. isolate()->global_handles()->InvokeSecondPassPhantomCallbacks(); // The VM is in the GC state until exiting this function. VMState<GC> state(isolate()); #ifdef V8_ENABLE_ALLOCATION_TIMEOUT // Reset the allocation timeout, but make sure to allow at least a few // allocations after a collection. The reason for this is that we have a lot // of allocation sequences and we assume that a garbage collection will allow // the subsequent allocation attempts to go through. if (FLAG_random_gc_interval > 0 || FLAG_gc_interval >= 0) { allocation_timeout_ = Max(6, NextAllocationTimeout(allocation_timeout_)); } #endif EnsureFillerObjectAtTop(); if (IsYoungGenerationCollector(collector) && !incremental_marking()->IsStopped()) { if (FLAG_trace_incremental_marking) { isolate()->PrintWithTimestamp( "[IncrementalMarking] Scavenge during marking.\n"); } } size_t freed_global_handles = 0; size_t committed_memory_before = 0; if (collector == MARK_COMPACTOR) { committed_memory_before = CommittedOldGenerationMemory(); } { tracer()->Start(collector, gc_reason, collector_reason); DCHECK(AllowHeapAllocation::IsAllowed()); DisallowHeapAllocation no_allocation_during_gc; GarbageCollectionPrologue(); { TimedHistogram* gc_type_timer = GCTypeTimer(collector); TimedHistogramScope histogram_timer_scope(gc_type_timer, isolate_); TRACE_EVENT0("v8", gc_type_timer->name()); TimedHistogram* gc_type_priority_timer = GCTypePriorityTimer(collector); OptionalTimedHistogramScopeMode mode = isolate_->IsMemorySavingsModeActive() ? OptionalTimedHistogramScopeMode::DONT_TAKE_TIME : OptionalTimedHistogramScopeMode::TAKE_TIME; OptionalTimedHistogramScope histogram_timer_priority_scope( gc_type_priority_timer, isolate_, mode); if (!IsYoungGenerationCollector(collector)) { PROFILE(isolate_, CodeMovingGCEvent()); } GCType gc_type = collector == MARK_COMPACTOR ? kGCTypeMarkSweepCompact : kGCTypeScavenge; { GCCallbacksScope scope(this); // Temporary override any embedder stack state as callbacks may create // their own state on the stack and recursively trigger GC. EmbedderStackStateScope embedder_scope( local_embedder_heap_tracer(), EmbedderHeapTracer::EmbedderStackState::kMayContainHeapPointers); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; AllowJavascriptExecution allow_js(isolate()); TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_PROLOGUE); VMState<EXTERNAL> state(isolate_); HandleScope handle_scope(isolate_); CallGCPrologueCallbacks(gc_type, kNoGCCallbackFlags); } } if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) { tp_heap_->CollectGarbage(); } else { freed_global_handles += PerformGarbageCollection(collector, gc_callback_flags); } // Clear is_current_gc_forced now that the current GC is complete. Do this // before GarbageCollectionEpilogue() since that could trigger another // unforced GC. is_current_gc_forced_ = false; { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_WEAK_GLOBAL_HANDLES); gc_post_processing_depth_++; { AllowHeapAllocation allow_allocation; AllowJavascriptExecution allow_js(isolate()); freed_global_handles += isolate_->global_handles()->PostGarbageCollectionProcessing( collector, gc_callback_flags); } gc_post_processing_depth_--; } { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; AllowJavascriptExecution allow_js(isolate()); TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_EPILOGUE); VMState<EXTERNAL> state(isolate_); HandleScope handle_scope(isolate_); CallGCEpilogueCallbacks(gc_type, gc_callback_flags); } } if (collector == MARK_COMPACTOR || collector == SCAVENGER) { tracer()->RecordGCPhasesHistograms(gc_type_timer); } } GarbageCollectionEpilogue(); if (collector == MARK_COMPACTOR && FLAG_track_detached_contexts) { isolate()->CheckDetachedContextsAfterGC(); } if (collector == MARK_COMPACTOR) { // Calculate used memory first, then committed memory. Following code // assumes that committed >= used, which might not hold when this is // calculated in the wrong order and background threads allocate // in-between. size_t used_memory_after = OldGenerationSizeOfObjects(); size_t committed_memory_after = CommittedOldGenerationMemory(); MemoryReducer::Event event; event.type = MemoryReducer::kMarkCompact; event.time_ms = MonotonicallyIncreasingTimeInMs(); // Trigger one more GC if // - this GC decreased committed memory, // - there is high fragmentation, event.next_gc_likely_to_collect_more = (committed_memory_before > committed_memory_after + MB) || HasHighFragmentation(used_memory_after, committed_memory_after); event.committed_memory = committed_memory_after; if (deserialization_complete_) { memory_reducer_->NotifyMarkCompact(event); } if (initial_max_old_generation_size_ < max_old_generation_size_ && used_memory_after < initial_max_old_generation_size_threshold_) { max_old_generation_size_ = initial_max_old_generation_size_; } } tracer()->Stop(collector); } if (collector == MARK_COMPACTOR && (gc_callback_flags & (kGCCallbackFlagForced | kGCCallbackFlagCollectAllAvailableGarbage)) != 0) { isolate()->CountUsage(v8::Isolate::kForcedGC); } collection_barrier_.CollectionPerformed(); // Start incremental marking for the next cycle. We do this only for scavenger // to avoid a loop where mark-compact causes another mark-compact. if (IsYoungGenerationCollector(collector)) { StartIncrementalMarkingIfAllocationLimitIsReached( GCFlagsForIncrementalMarking(), kGCCallbackScheduleIdleGarbageCollection); } return freed_global_handles > 0; } int Heap::NotifyContextDisposed(bool dependant_context) { if (!dependant_context) { tracer()->ResetSurvivalEvents(); old_generation_size_configured_ = false; old_generation_allocation_limit_ = initial_old_generation_size_; MemoryReducer::Event event; event.type = MemoryReducer::kPossibleGarbage; event.time_ms = MonotonicallyIncreasingTimeInMs(); memory_reducer_->NotifyPossibleGarbage(event); } isolate()->AbortConcurrentOptimization(BlockingBehavior::kDontBlock); if (!isolate()->context().is_null()) { RemoveDirtyFinalizationRegistriesOnContext(isolate()->raw_native_context()); isolate()->raw_native_context().set_retained_maps( ReadOnlyRoots(this).empty_weak_array_list()); } tracer()->AddContextDisposalTime(MonotonicallyIncreasingTimeInMs()); return ++contexts_disposed_; } void Heap::StartIncrementalMarking(int gc_flags, GarbageCollectionReason gc_reason, GCCallbackFlags gc_callback_flags) { DCHECK(incremental_marking()->IsStopped()); SafepointScope safepoint(this); set_current_gc_flags(gc_flags); current_gc_callback_flags_ = gc_callback_flags; incremental_marking()->Start(gc_reason); } void Heap::StartIncrementalMarkingIfAllocationLimitIsReached( int gc_flags, const GCCallbackFlags gc_callback_flags) { if (incremental_marking()->IsStopped()) { IncrementalMarkingLimit reached_limit = IncrementalMarkingLimitReached(); if (reached_limit == IncrementalMarkingLimit::kSoftLimit) { incremental_marking()->incremental_marking_job()->ScheduleTask(this); } else if (reached_limit == IncrementalMarkingLimit::kHardLimit) { StartIncrementalMarking( gc_flags, OldGenerationSpaceAvailable() <= new_space_->Capacity() ? GarbageCollectionReason::kAllocationLimit : GarbageCollectionReason::kGlobalAllocationLimit, gc_callback_flags); } } } void Heap::StartIncrementalMarkingIfAllocationLimitIsReachedBackground() { if (!incremental_marking()->IsStopped() || !incremental_marking()->CanBeActivated()) { return; } const size_t old_generation_space_available = OldGenerationSpaceAvailable(); const base::Optional<size_t> global_memory_available = GlobalMemoryAvailable(); if (old_generation_space_available < new_space_->Capacity() || (global_memory_available && *global_memory_available < new_space_->Capacity())) { incremental_marking()->incremental_marking_job()->ScheduleTask(this); } } void Heap::StartIdleIncrementalMarking( GarbageCollectionReason gc_reason, const GCCallbackFlags gc_callback_flags) { StartIncrementalMarking(kReduceMemoryFootprintMask, gc_reason, gc_callback_flags); } void Heap::MoveRange(HeapObject dst_object, const ObjectSlot dst_slot, const ObjectSlot src_slot, int len, WriteBarrierMode mode) { DCHECK_NE(len, 0); DCHECK_NE(dst_object.map(), ReadOnlyRoots(this).fixed_cow_array_map()); const ObjectSlot dst_end(dst_slot + len); // Ensure no range overflow. DCHECK(dst_slot < dst_end); DCHECK(src_slot < src_slot + len); if (FLAG_concurrent_marking && incremental_marking()->IsMarking()) { if (dst_slot < src_slot) { // Copy tagged values forward using relaxed load/stores that do not // involve value decompression. const AtomicSlot atomic_dst_end(dst_end); AtomicSlot dst(dst_slot); AtomicSlot src(src_slot); while (dst < atomic_dst_end) { *dst = *src; ++dst; ++src; } } else { // Copy tagged values backwards using relaxed load/stores that do not // involve value decompression. const AtomicSlot atomic_dst_begin(dst_slot); AtomicSlot dst(dst_slot + len - 1); AtomicSlot src(src_slot + len - 1); while (dst >= atomic_dst_begin) { *dst = *src; --dst; --src; } } } else { MemMove(dst_slot.ToVoidPtr(), src_slot.ToVoidPtr(), len * kTaggedSize); } if (mode == SKIP_WRITE_BARRIER) return; WriteBarrierForRange(dst_object, dst_slot, dst_end); } // Instantiate Heap::CopyRange() for ObjectSlot and MaybeObjectSlot. template void Heap::CopyRange<ObjectSlot>(HeapObject dst_object, ObjectSlot dst_slot, ObjectSlot src_slot, int len, WriteBarrierMode mode); template void Heap::CopyRange<MaybeObjectSlot>(HeapObject dst_object, MaybeObjectSlot dst_slot, MaybeObjectSlot src_slot, int len, WriteBarrierMode mode); template <typename TSlot> void Heap::CopyRange(HeapObject dst_object, const TSlot dst_slot, const TSlot src_slot, int len, WriteBarrierMode mode) { DCHECK_NE(len, 0); DCHECK_NE(dst_object.map(), ReadOnlyRoots(this).fixed_cow_array_map()); const TSlot dst_end(dst_slot + len); // Ensure ranges do not overlap. DCHECK(dst_end <= src_slot || (src_slot + len) <= dst_slot); if (FLAG_concurrent_marking && incremental_marking()->IsMarking()) { // Copy tagged values using relaxed load/stores that do not involve value // decompression. const AtomicSlot atomic_dst_end(dst_end); AtomicSlot dst(dst_slot); AtomicSlot src(src_slot); while (dst < atomic_dst_end) { *dst = *src; ++dst; ++src; } } else { MemCopy(dst_slot.ToVoidPtr(), src_slot.ToVoidPtr(), len * kTaggedSize); } if (mode == SKIP_WRITE_BARRIER) return; WriteBarrierForRange(dst_object, dst_slot, dst_end); } #ifdef VERIFY_HEAP // Helper class for verifying the string table. class StringTableVerifier : public ObjectVisitor { public: explicit StringTableVerifier(Isolate* isolate) : isolate_(isolate) {} void VisitPointers(HeapObject host, ObjectSlot start, ObjectSlot end) override { // Visit all HeapObject pointers in [start, end). for (ObjectSlot p = start; p < end; ++p) { DCHECK(!HasWeakHeapObjectTag(*p)); if ((*p).IsHeapObject()) { HeapObject object = HeapObject::cast(*p); // Check that the string is actually internalized. CHECK(object.IsTheHole(isolate_) || object.IsUndefined(isolate_) || object.IsInternalizedString()); } } } void VisitPointers(HeapObject host, MaybeObjectSlot start, MaybeObjectSlot end) override { UNREACHABLE(); } void VisitCodeTarget(Code host, RelocInfo* rinfo) override { UNREACHABLE(); } void VisitEmbeddedPointer(Code host, RelocInfo* rinfo) override { UNREACHABLE(); } private: Isolate* isolate_; }; static void VerifyStringTable(Isolate* isolate) { StringTableVerifier verifier(isolate); isolate->heap()->string_table().IterateElements(&verifier); } #endif // VERIFY_HEAP bool Heap::ReserveSpace(Reservation* reservations, std::vector<Address>* maps) { bool gc_performed = true; int counter = 0; static const int kThreshold = 20; while (gc_performed && counter++ < kThreshold) { gc_performed = false; for (int space = FIRST_SPACE; space < static_cast<int>(SnapshotSpace::kNumberOfHeapSpaces); space++) { Reservation* reservation = &reservations[space]; DCHECK_LE(1, reservation->size()); if (reservation->at(0).size == 0) { DCHECK_EQ(1, reservation->size()); continue; } bool perform_gc = false; if (space == MAP_SPACE) { // We allocate each map individually to avoid fragmentation. maps->clear(); DCHECK_LE(reservation->size(), 2); int reserved_size = 0; for (const Chunk& c : *reservation) reserved_size += c.size; DCHECK_EQ(0, reserved_size % Map::kSize); int num_maps = reserved_size / Map::kSize; for (int i = 0; i < num_maps; i++) { AllocationResult allocation; #if V8_ENABLE_THIRD_PARTY_HEAP_BOOL allocation = AllocateRaw(Map::kSize, AllocationType::kMap, AllocationOrigin::kRuntime, kWordAligned); #else allocation = map_space()->AllocateRawUnaligned(Map::kSize); #endif HeapObject free_space; if (allocation.To(&free_space)) { // Mark with a free list node, in case we have a GC before // deserializing. Address free_space_address = free_space.address(); CreateFillerObjectAt(free_space_address, Map::kSize, ClearRecordedSlots::kNo); maps->push_back(free_space_address); } else { perform_gc = true; break; } } } else if (space == LO_SPACE) { // Just check that we can allocate during deserialization. DCHECK_LE(reservation->size(), 2); int reserved_size = 0; for (const Chunk& c : *reservation) reserved_size += c.size; perform_gc = !CanExpandOldGeneration(reserved_size); } else { for (auto& chunk : *reservation) { AllocationResult allocation; int size = chunk.size; DCHECK_LE(static_cast<size_t>(size), MemoryChunkLayout::AllocatableMemoryInMemoryChunk( static_cast<AllocationSpace>(space))); #if V8_ENABLE_THIRD_PARTY_HEAP_BOOL AllocationType type = (space == CODE_SPACE) ? AllocationType::kCode : (space == RO_SPACE) ? AllocationType::kReadOnly : AllocationType::kYoung; AllocationAlignment align = (space == CODE_SPACE) ? kCodeAligned : kWordAligned; allocation = AllocateRaw(size, type, AllocationOrigin::kRuntime, align); #else if (space == NEW_SPACE) { allocation = new_space()->AllocateRawUnaligned(size); } else if (space == RO_SPACE) { allocation = read_only_space()->AllocateRaw( size, AllocationAlignment::kWordAligned); } else { // The deserializer will update the skip list. allocation = paged_space(space)->AllocateRawUnaligned(size); } #endif HeapObject free_space; if (allocation.To(&free_space)) { // Mark with a free list node, in case we have a GC before // deserializing. Address free_space_address = free_space.address(); CreateFillerObjectAt(free_space_address, size, ClearRecordedSlots::kNo); DCHECK(IsPreAllocatedSpace(static_cast<SnapshotSpace>(space))); chunk.start = free_space_address; chunk.end = free_space_address + size; } else { perform_gc = true; break; } } } if (perform_gc) { // We cannot perfom a GC with an uninitialized isolate. This check // fails for example if the max old space size is chosen unwisely, // so that we cannot allocate space to deserialize the initial heap. if (!deserialization_complete_) { V8::FatalProcessOutOfMemory( isolate(), "insufficient memory to create an Isolate"); } if (space == NEW_SPACE) { CollectGarbage(NEW_SPACE, GarbageCollectionReason::kDeserializer); } else { if (counter > 1) { CollectAllGarbage(kReduceMemoryFootprintMask, GarbageCollectionReason::kDeserializer); } else { CollectAllGarbage(kNoGCFlags, GarbageCollectionReason::kDeserializer); } } gc_performed = true; break; // Abort for-loop over spaces and retry. } } } return !gc_performed; } void Heap::EnsureFromSpaceIsCommitted() { if (new_space_->CommitFromSpaceIfNeeded()) return; // Committing memory to from space failed. // Memory is exhausted and we will die. FatalProcessOutOfMemory("Committing semi space failed."); } void Heap::CollectionBarrier::CollectionPerformed() { base::MutexGuard guard(&mutex_); gc_requested_ = false; cond_.NotifyAll(); } void Heap::CollectionBarrier::ShutdownRequested() { base::MutexGuard guard(&mutex_); shutdown_requested_ = true; cond_.NotifyAll(); } void Heap::CollectionBarrier::Wait() { base::MutexGuard guard(&mutex_); if (shutdown_requested_) return; if (!gc_requested_) { heap_->MemoryPressureNotification(MemoryPressureLevel::kCritical, false); gc_requested_ = true; } while (gc_requested_ && !shutdown_requested_) { cond_.Wait(&mutex_); } } void Heap::RequestAndWaitForCollection() { collection_barrier_.Wait(); } void Heap::UpdateSurvivalStatistics(int start_new_space_size) { if (start_new_space_size == 0) return; promotion_ratio_ = (static_cast<double>(promoted_objects_size_) / static_cast<double>(start_new_space_size) * 100); if (previous_semi_space_copied_object_size_ > 0) { promotion_rate_ = (static_cast<double>(promoted_objects_size_) / static_cast<double>(previous_semi_space_copied_object_size_) * 100); } else { promotion_rate_ = 0; } semi_space_copied_rate_ = (static_cast<double>(semi_space_copied_object_size_) / static_cast<double>(start_new_space_size) * 100); double survival_rate = promotion_ratio_ + semi_space_copied_rate_; tracer()->AddSurvivalRatio(survival_rate); } size_t Heap::PerformGarbageCollection( GarbageCollector collector, const v8::GCCallbackFlags gc_callback_flags) { DisallowJavascriptExecution no_js(isolate()); base::Optional<SafepointScope> optional_safepoint_scope; if (FLAG_local_heaps) { optional_safepoint_scope.emplace(this); } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif tracer()->StartInSafepoint(); GarbageCollectionPrologueInSafepoint(); EnsureFromSpaceIsCommitted(); size_t start_young_generation_size = Heap::new_space()->Size() + new_lo_space()->SizeOfObjects(); switch (collector) { case MARK_COMPACTOR: MarkCompact(); break; case MINOR_MARK_COMPACTOR: MinorMarkCompact(); break; case SCAVENGER: Scavenge(); break; } ProcessPretenuringFeedback(); UpdateSurvivalStatistics(static_cast<int>(start_young_generation_size)); ConfigureInitialOldGenerationSize(); if (collector != MARK_COMPACTOR) { // Objects that died in the new space might have been accounted // as bytes marked ahead of schedule by the incremental marker. incremental_marking()->UpdateMarkedBytesAfterScavenge( start_young_generation_size - SurvivedYoungObjectSize()); } if (!fast_promotion_mode_ || collector == MARK_COMPACTOR) { ComputeFastPromotionMode(); } isolate_->counters()->objs_since_last_young()->Set(0); isolate_->eternal_handles()->PostGarbageCollectionProcessing(); // Update relocatables. Relocatable::PostGarbageCollectionProcessing(isolate_); size_t freed_global_handles; { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_WEAK_GLOBAL_HANDLES); // First round weak callbacks are not supposed to allocate and trigger // nested GCs. freed_global_handles = isolate_->global_handles()->InvokeFirstPassWeakCallbacks(); } if (collector == MARK_COMPACTOR) { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EMBEDDER_TRACING_EPILOGUE); // TraceEpilogue may trigger operations that invalidate global handles. It // has to be called *after* all other operations that potentially touch and // reset global handles. It is also still part of the main garbage // collection pause and thus needs to be called *before* any operation that // can potentially trigger recursive garbage local_embedder_heap_tracer()->TraceEpilogue(); } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif RecomputeLimits(collector); GarbageCollectionEpilogueInSafepoint(); tracer()->StopInSafepoint(); return freed_global_handles; } void Heap::RecomputeLimits(GarbageCollector collector) { if (!((collector == MARK_COMPACTOR) || (HasLowYoungGenerationAllocationRate() && old_generation_size_configured_))) { return; } double v8_gc_speed = tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond(); double v8_mutator_speed = tracer()->CurrentOldGenerationAllocationThroughputInBytesPerMillisecond(); double v8_growing_factor = MemoryController<V8HeapTrait>::GrowingFactor( this, max_old_generation_size_, v8_gc_speed, v8_mutator_speed); double global_growing_factor = 0; if (UseGlobalMemoryScheduling()) { DCHECK_NOT_NULL(local_embedder_heap_tracer()); double embedder_gc_speed = tracer()->EmbedderSpeedInBytesPerMillisecond(); double embedder_speed = tracer()->CurrentEmbedderAllocationThroughputInBytesPerMillisecond(); double embedder_growing_factor = (embedder_gc_speed > 0 && embedder_speed > 0) ? MemoryController<GlobalMemoryTrait>::GrowingFactor( this, max_global_memory_size_, embedder_gc_speed, embedder_speed) : 0; global_growing_factor = Max(v8_growing_factor, embedder_growing_factor); } size_t old_gen_size = OldGenerationSizeOfObjects(); size_t new_space_capacity = new_space()->Capacity(); HeapGrowingMode mode = CurrentHeapGrowingMode(); if (collector == MARK_COMPACTOR) { // Register the amount of external allocated memory. isolate()->isolate_data()->external_memory_low_since_mark_compact_ = isolate()->isolate_data()->external_memory_; isolate()->isolate_data()->external_memory_limit_ = isolate()->isolate_data()->external_memory_ + kExternalAllocationSoftLimit; old_generation_allocation_limit_ = MemoryController<V8HeapTrait>::CalculateAllocationLimit( this, old_gen_size, min_old_generation_size_, max_old_generation_size_, new_space_capacity, v8_growing_factor, mode); if (UseGlobalMemoryScheduling()) { DCHECK_GT(global_growing_factor, 0); global_allocation_limit_ = MemoryController<GlobalMemoryTrait>::CalculateAllocationLimit( this, GlobalSizeOfObjects(), min_global_memory_size_, max_global_memory_size_, new_space_capacity, global_growing_factor, mode); } CheckIneffectiveMarkCompact( old_gen_size, tracer()->AverageMarkCompactMutatorUtilization()); } else if (HasLowYoungGenerationAllocationRate() && old_generation_size_configured_) { size_t new_old_generation_limit = MemoryController<V8HeapTrait>::CalculateAllocationLimit( this, old_gen_size, min_old_generation_size_, max_old_generation_size_, new_space_capacity, v8_growing_factor, mode); if (new_old_generation_limit < old_generation_allocation_limit_) { old_generation_allocation_limit_ = new_old_generation_limit; } if (UseGlobalMemoryScheduling()) { DCHECK_GT(global_growing_factor, 0); size_t new_global_limit = MemoryController<GlobalMemoryTrait>::CalculateAllocationLimit( this, GlobalSizeOfObjects(), min_global_memory_size_, max_global_memory_size_, new_space_capacity, global_growing_factor, mode); if (new_global_limit < global_allocation_limit_) { global_allocation_limit_ = new_global_limit; } } } } void Heap::CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags) { RuntimeCallTimerScope runtime_timer( isolate(), RuntimeCallCounterId::kGCPrologueCallback); for (const GCCallbackTuple& info : gc_prologue_callbacks_) { if (gc_type & info.gc_type) { v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this->isolate()); info.callback(isolate, gc_type, flags, info.data); } } } void Heap::CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags) { RuntimeCallTimerScope runtime_timer( isolate(), RuntimeCallCounterId::kGCEpilogueCallback); for (const GCCallbackTuple& info : gc_epilogue_callbacks_) { if (gc_type & info.gc_type) { v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this->isolate()); info.callback(isolate, gc_type, flags, info.data); } } } void Heap::MarkCompact() { PauseAllocationObserversScope pause_observers(this); SetGCState(MARK_COMPACT); LOG(isolate_, ResourceEvent("markcompact", "begin")); CodeSpaceMemoryModificationScope code_modifcation(this); UpdateOldGenerationAllocationCounter(); uint64_t size_of_objects_before_gc = SizeOfObjects(); mark_compact_collector()->Prepare(); ms_count_++; MarkCompactPrologue(); mark_compact_collector()->CollectGarbage(); LOG(isolate_, ResourceEvent("markcompact", "end")); MarkCompactEpilogue(); if (FLAG_allocation_site_pretenuring) { EvaluateOldSpaceLocalPretenuring(size_of_objects_before_gc); } old_generation_size_configured_ = true; // This should be updated before PostGarbageCollectionProcessing, which // can cause another GC. Take into account the objects promoted during // GC. old_generation_allocation_counter_at_last_gc_ += static_cast<size_t>(promoted_objects_size_); old_generation_size_at_last_gc_ = OldGenerationSizeOfObjects(); global_memory_at_last_gc_ = GlobalSizeOfObjects(); } void Heap::MinorMarkCompact() { #ifdef ENABLE_MINOR_MC DCHECK(FLAG_minor_mc); PauseAllocationObserversScope pause_observers(this); SetGCState(MINOR_MARK_COMPACT); LOG(isolate_, ResourceEvent("MinorMarkCompact", "begin")); TRACE_GC(tracer(), GCTracer::Scope::MINOR_MC); AlwaysAllocateScope always_allocate(this); IncrementalMarking::PauseBlackAllocationScope pause_black_allocation( incremental_marking()); ConcurrentMarking::PauseScope pause_scope(concurrent_marking()); minor_mark_compact_collector()->CollectGarbage(); LOG(isolate_, ResourceEvent("MinorMarkCompact", "end")); SetGCState(NOT_IN_GC); #else UNREACHABLE(); #endif // ENABLE_MINOR_MC } void Heap::MarkCompactEpilogue() { TRACE_GC(tracer(), GCTracer::Scope::MC_EPILOGUE); SetGCState(NOT_IN_GC); isolate_->counters()->objs_since_last_full()->Set(0); incremental_marking()->Epilogue(); DCHECK(incremental_marking()->IsStopped()); } void Heap::MarkCompactPrologue() { TRACE_GC(tracer(), GCTracer::Scope::MC_PROLOGUE); isolate_->descriptor_lookup_cache()->Clear(); RegExpResultsCache::Clear(string_split_cache()); RegExpResultsCache::Clear(regexp_multiple_cache()); isolate_->compilation_cache()->MarkCompactPrologue(); FlushNumberStringCache(); } void Heap::CheckNewSpaceExpansionCriteria() { if (new_space_->TotalCapacity() < new_space_->MaximumCapacity() && survived_since_last_expansion_ > new_space_->TotalCapacity()) { // Grow the size of new space if there is room to grow, and enough data // has survived scavenge since the last expansion. new_space_->Grow(); survived_since_last_expansion_ = 0; } new_lo_space()->SetCapacity(new_space()->Capacity()); } void Heap::EvacuateYoungGeneration() { TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_FAST_PROMOTE); base::MutexGuard guard(relocation_mutex()); ConcurrentMarking::PauseScope pause_scope(concurrent_marking()); if (!FLAG_concurrent_marking) { DCHECK(fast_promotion_mode_); DCHECK( CanExpandOldGeneration(new_space()->Size() + new_lo_space()->Size())); } mark_compact_collector()->sweeper()->EnsureIterabilityCompleted(); SetGCState(SCAVENGE); LOG(isolate_, ResourceEvent("scavenge", "begin")); // Move pages from new->old generation. PageRange range(new_space()->first_allocatable_address(), new_space()->top()); for (auto it = range.begin(); it != range.end();) { Page* p = (*++it)->prev_page(); new_space()->from_space().RemovePage(p); Page::ConvertNewToOld(p); if (incremental_marking()->IsMarking()) mark_compact_collector()->RecordLiveSlotsOnPage(p); } // Reset new space. if (!new_space()->Rebalance()) { FatalProcessOutOfMemory("NewSpace::Rebalance"); } new_space()->ResetLinearAllocationArea(); new_space()->set_age_mark(new_space()->top()); for (auto it = new_lo_space()->begin(); it != new_lo_space()->end();) { LargePage* page = *it; // Increment has to happen after we save the page, because it is going to // be removed below. it++; lo_space()->PromoteNewLargeObject(page); } // Fix up special trackers. external_string_table_.PromoteYoung(); // GlobalHandles are updated in PostGarbageCollectonProcessing size_t promoted = new_space()->Size() + new_lo_space()->Size(); IncrementYoungSurvivorsCounter(promoted); IncrementPromotedObjectsSize(promoted); IncrementSemiSpaceCopiedObjectSize(0); LOG(isolate_, ResourceEvent("scavenge", "end")); SetGCState(NOT_IN_GC); } void Heap::Scavenge() { if ((fast_promotion_mode_ && CanExpandOldGeneration(new_space()->Size() + new_lo_space()->Size()))) { tracer()->NotifyYoungGenerationHandling( YoungGenerationHandling::kFastPromotionDuringScavenge); EvacuateYoungGeneration(); return; } tracer()->NotifyYoungGenerationHandling( YoungGenerationHandling::kRegularScavenge); TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE); base::MutexGuard guard(relocation_mutex()); ConcurrentMarking::PauseScope pause_scope(concurrent_marking()); // There are soft limits in the allocation code, designed to trigger a mark // sweep collection by failing allocations. There is no sense in trying to // trigger one during scavenge: scavenges allocation should always succeed. AlwaysAllocateScope scope(this); // Bump-pointer allocations done during scavenge are not real allocations. // Pause the inline allocation steps. PauseAllocationObserversScope pause_observers(this); IncrementalMarking::PauseBlackAllocationScope pause_black_allocation( incremental_marking()); mark_compact_collector()->sweeper()->EnsureIterabilityCompleted(); SetGCState(SCAVENGE); // Flip the semispaces. After flipping, to space is empty, from space has // live objects. new_space()->Flip(); new_space()->ResetLinearAllocationArea(); // We also flip the young generation large object space. All large objects // will be in the from space. new_lo_space()->Flip(); new_lo_space()->ResetPendingObject(); // Implements Cheney's copying algorithm LOG(isolate_, ResourceEvent("scavenge", "begin")); scavenger_collector_->CollectGarbage(); LOG(isolate_, ResourceEvent("scavenge", "end")); SetGCState(NOT_IN_GC); } void Heap::ComputeFastPromotionMode() { const size_t survived_in_new_space = survived_last_scavenge_ * 100 / new_space_->Capacity(); fast_promotion_mode_ = !FLAG_optimize_for_size && FLAG_fast_promotion_new_space && !ShouldReduceMemory() && new_space_->IsAtMaximumCapacity() && survived_in_new_space >= kMinPromotedPercentForFastPromotionMode; if (FLAG_trace_gc_verbose && !FLAG_trace_gc_ignore_scavenger) { PrintIsolate(isolate(), "Fast promotion mode: %s survival rate: %zu%%\n", fast_promotion_mode_ ? "true" : "false", survived_in_new_space); } } void Heap::UnprotectAndRegisterMemoryChunk(MemoryChunk* chunk) { if (unprotected_memory_chunks_registry_enabled_) { base::MutexGuard guard(&unprotected_memory_chunks_mutex_); if (unprotected_memory_chunks_.insert(chunk).second) { chunk->SetReadAndWritable(); } } } void Heap::UnprotectAndRegisterMemoryChunk(HeapObject object) { UnprotectAndRegisterMemoryChunk(MemoryChunk::FromHeapObject(object)); } void Heap::UnregisterUnprotectedMemoryChunk(MemoryChunk* chunk) { unprotected_memory_chunks_.erase(chunk); } void Heap::ProtectUnprotectedMemoryChunks() { DCHECK(unprotected_memory_chunks_registry_enabled_); for (auto chunk = unprotected_memory_chunks_.begin(); chunk != unprotected_memory_chunks_.end(); chunk++) { CHECK(memory_allocator()->IsMemoryChunkExecutable(*chunk)); (*chunk)->SetDefaultCodePermissions(); } unprotected_memory_chunks_.clear(); } bool Heap::ExternalStringTable::Contains(String string) { for (size_t i = 0; i < young_strings_.size(); ++i) { if (young_strings_[i] == string) return true; } for (size_t i = 0; i < old_strings_.size(); ++i) { if (old_strings_[i] == string) return true; } return false; } void Heap::UpdateExternalString(String string, size_t old_payload, size_t new_payload) { DCHECK(string.IsExternalString()); Page* page = Page::FromHeapObject(string); if (old_payload > new_payload) { page->DecrementExternalBackingStoreBytes( ExternalBackingStoreType::kExternalString, old_payload - new_payload); } else { page->IncrementExternalBackingStoreBytes( ExternalBackingStoreType::kExternalString, new_payload - old_payload); } } String Heap::UpdateYoungReferenceInExternalStringTableEntry(Heap* heap, FullObjectSlot p) { HeapObject obj = HeapObject::cast(*p); MapWord first_word = obj.map_word(); String new_string; if (InFromPage(obj)) { if (!first_word.IsForwardingAddress()) { // Unreachable external string can be finalized. String string = String::cast(obj); if (!string.IsExternalString()) { // Original external string has been internalized. DCHECK(string.IsThinString()); return String(); } heap->FinalizeExternalString(string); return String(); } new_string = String::cast(first_word.ToForwardingAddress()); } else { new_string = String::cast(obj); } // String is still reachable. if (new_string.IsThinString()) { // Filtering Thin strings out of the external string table. return String(); } else if (new_string.IsExternalString()) { MemoryChunk::MoveExternalBackingStoreBytes( ExternalBackingStoreType::kExternalString, Page::FromAddress((*p).ptr()), Page::FromHeapObject(new_string), ExternalString::cast(new_string).ExternalPayloadSize()); return new_string; } // Internalization can replace external strings with non-external strings. return new_string.IsExternalString() ? new_string : String(); } void Heap::ExternalStringTable::VerifyYoung() { #ifdef DEBUG std::set<String> visited_map; std::map<MemoryChunk*, size_t> size_map; ExternalBackingStoreType type = ExternalBackingStoreType::kExternalString; for (size_t i = 0; i < young_strings_.size(); ++i) { String obj = String::cast(young_strings_[i]); MemoryChunk* mc = MemoryChunk::FromHeapObject(obj); DCHECK(mc->InYoungGeneration()); DCHECK(heap_->InYoungGeneration(obj)); DCHECK(!obj.IsTheHole(heap_->isolate())); DCHECK(obj.IsExternalString()); // Note: we can have repeated elements in the table. DCHECK_EQ(0, visited_map.count(obj)); visited_map.insert(obj); size_map[mc] += ExternalString::cast(obj).ExternalPayloadSize(); } for (std::map<MemoryChunk*, size_t>::iterator it = size_map.begin(); it != size_map.end(); it++) DCHECK_EQ(it->first->ExternalBackingStoreBytes(type), it->second); #endif } void Heap::ExternalStringTable::Verify() { #ifdef DEBUG std::set<String> visited_map; std::map<MemoryChunk*, size_t> size_map; ExternalBackingStoreType type = ExternalBackingStoreType::kExternalString; VerifyYoung(); for (size_t i = 0; i < old_strings_.size(); ++i) { String obj = String::cast(old_strings_[i]); MemoryChunk* mc = MemoryChunk::FromHeapObject(obj); DCHECK(!mc->InYoungGeneration()); DCHECK(!heap_->InYoungGeneration(obj)); DCHECK(!obj.IsTheHole(heap_->isolate())); DCHECK(obj.IsExternalString()); // Note: we can have repeated elements in the table. DCHECK_EQ(0, visited_map.count(obj)); visited_map.insert(obj); size_map[mc] += ExternalString::cast(obj).ExternalPayloadSize(); } for (std::map<MemoryChunk*, size_t>::iterator it = size_map.begin(); it != size_map.end(); it++) DCHECK_EQ(it->first->ExternalBackingStoreBytes(type), it->second); #endif } void Heap::ExternalStringTable::UpdateYoungReferences( Heap::ExternalStringTableUpdaterCallback updater_func) { if (young_strings_.empty()) return; FullObjectSlot start(young_strings_.data()); FullObjectSlot end(young_strings_.data() + young_strings_.size()); FullObjectSlot last = start; for (FullObjectSlot p = start; p < end; ++p) { String target = updater_func(heap_, p); if (target.is_null()) continue; DCHECK(target.IsExternalString()); if (InYoungGeneration(target)) { // String is still in new space. Update the table entry. last.store(target); ++last; } else { // String got promoted. Move it to the old string list. old_strings_.push_back(target); } } DCHECK(last <= end); young_strings_.resize(last - start); #ifdef VERIFY_HEAP if (FLAG_verify_heap) { VerifyYoung(); } #endif } void Heap::ExternalStringTable::PromoteYoung() { old_strings_.reserve(old_strings_.size() + young_strings_.size()); std::move(std::begin(young_strings_), std::end(young_strings_), std::back_inserter(old_strings_)); young_strings_.clear(); } void Heap::ExternalStringTable::IterateYoung(RootVisitor* v) { if (!young_strings_.empty()) { v->VisitRootPointers( Root::kExternalStringsTable, nullptr, FullObjectSlot(young_strings_.data()), FullObjectSlot(young_strings_.data() + young_strings_.size())); } } void Heap::ExternalStringTable::IterateAll(RootVisitor* v) { IterateYoung(v); if (!old_strings_.empty()) { v->VisitRootPointers( Root::kExternalStringsTable, nullptr, FullObjectSlot(old_strings_.data()), FullObjectSlot(old_strings_.data() + old_strings_.size())); } } void Heap::UpdateYoungReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func) { external_string_table_.UpdateYoungReferences(updater_func); } void Heap::ExternalStringTable::UpdateReferences( Heap::ExternalStringTableUpdaterCallback updater_func) { if (old_strings_.size() > 0) { FullObjectSlot start(old_strings_.data()); FullObjectSlot end(old_strings_.data() + old_strings_.size()); for (FullObjectSlot p = start; p < end; ++p) p.store(updater_func(heap_, p)); } UpdateYoungReferences(updater_func); } void Heap::UpdateReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func) { external_string_table_.UpdateReferences(updater_func); } void Heap::ProcessAllWeakReferences(WeakObjectRetainer* retainer) { ProcessNativeContexts(retainer); ProcessAllocationSites(retainer); ProcessDirtyJSFinalizationRegistries(retainer); } void Heap::ProcessYoungWeakReferences(WeakObjectRetainer* retainer) { ProcessNativeContexts(retainer); } void Heap::ProcessNativeContexts(WeakObjectRetainer* retainer) { Object head = VisitWeakList<Context>(this, native_contexts_list(), retainer); // Update the head of the list of contexts. set_native_contexts_list(head); } void Heap::ProcessAllocationSites(WeakObjectRetainer* retainer) { Object allocation_site_obj = VisitWeakList<AllocationSite>(this, allocation_sites_list(), retainer); set_allocation_sites_list(allocation_site_obj); } void Heap::ProcessDirtyJSFinalizationRegistries(WeakObjectRetainer* retainer) { Object head = VisitWeakList<JSFinalizationRegistry>( this, dirty_js_finalization_registries_list(), retainer); set_dirty_js_finalization_registries_list(head); // If the list is empty, set the tail to undefined. Otherwise the tail is set // by WeakListVisitor<JSFinalizationRegistry>::VisitLiveObject. if (head.IsUndefined(isolate())) { set_dirty_js_finalization_registries_list_tail(head); } } void Heap::ProcessWeakListRoots(WeakObjectRetainer* retainer) { set_native_contexts_list(retainer->RetainAs(native_contexts_list())); set_allocation_sites_list(retainer->RetainAs(allocation_sites_list())); set_dirty_js_finalization_registries_list( retainer->RetainAs(dirty_js_finalization_registries_list())); set_dirty_js_finalization_registries_list_tail( retainer->RetainAs(dirty_js_finalization_registries_list_tail())); } void Heap::ForeachAllocationSite( Object list, const std::function<void(AllocationSite)>& visitor) { DisallowHeapAllocation disallow_heap_allocation; Object current = list; while (current.IsAllocationSite()) { AllocationSite site = AllocationSite::cast(current); visitor(site); Object current_nested = site.nested_site(); while (current_nested.IsAllocationSite()) { AllocationSite nested_site = AllocationSite::cast(current_nested); visitor(nested_site); current_nested = nested_site.nested_site(); } current = site.weak_next(); } } void Heap::ResetAllAllocationSitesDependentCode(AllocationType allocation) { DisallowHeapAllocation no_allocation_scope; bool marked = false; ForeachAllocationSite(allocation_sites_list(), [&marked, allocation, this](AllocationSite site) { if (site.GetAllocationType() == allocation) { site.ResetPretenureDecision(); site.set_deopt_dependent_code(true); marked = true; RemoveAllocationSitePretenuringFeedback(site); return; } }); if (marked) isolate_->stack_guard()->RequestDeoptMarkedAllocationSites(); } void Heap::EvaluateOldSpaceLocalPretenuring( uint64_t size_of_objects_before_gc) { uint64_t size_of_objects_after_gc = SizeOfObjects(); double old_generation_survival_rate = (static_cast<double>(size_of_objects_after_gc) * 100) / static_cast<double>(size_of_objects_before_gc); if (old_generation_survival_rate < kOldSurvivalRateLowThreshold) { // Too many objects died in the old generation, pretenuring of wrong // allocation sites may be the cause for that. We have to deopt all // dependent code registered in the allocation sites to re-evaluate // our pretenuring decisions. ResetAllAllocationSitesDependentCode(AllocationType::kOld); if (FLAG_trace_pretenuring) { PrintF( "Deopt all allocation sites dependent code due to low survival " "rate in the old generation %f\n", old_generation_survival_rate); } } } void Heap::VisitExternalResources(v8::ExternalResourceVisitor* visitor) { DisallowHeapAllocation no_allocation; // All external strings are listed in the external string table. class ExternalStringTableVisitorAdapter : public RootVisitor { public: explicit ExternalStringTableVisitorAdapter( Isolate* isolate, v8::ExternalResourceVisitor* visitor) : isolate_(isolate), visitor_(visitor) {} void VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) override { for (FullObjectSlot p = start; p < end; ++p) { DCHECK((*p).IsExternalString()); visitor_->VisitExternalString( Utils::ToLocal(Handle<String>(String::cast(*p), isolate_))); } } private: Isolate* isolate_; v8::ExternalResourceVisitor* visitor_; } external_string_table_visitor(isolate(), visitor); external_string_table_.IterateAll(&external_string_table_visitor); } STATIC_ASSERT(IsAligned(FixedDoubleArray::kHeaderSize, kDoubleAlignment)); #ifdef V8_COMPRESS_POINTERS // TODO(ishell, v8:8875): When pointer compression is enabled the kHeaderSize // is only kTaggedSize aligned but we can keep using unaligned access since // both x64 and arm64 architectures (where pointer compression supported) // allow unaligned access to doubles. STATIC_ASSERT(IsAligned(ByteArray::kHeaderSize, kTaggedSize)); #else STATIC_ASSERT(IsAligned(ByteArray::kHeaderSize, kDoubleAlignment)); #endif #ifdef V8_HOST_ARCH_32_BIT // NOLINTNEXTLINE(runtime/references) (false positive) STATIC_ASSERT((HeapNumber::kValueOffset & kDoubleAlignmentMask) == kTaggedSize); #endif int Heap::GetMaximumFillToAlign(AllocationAlignment alignment) { switch (alignment) { case kWordAligned: return 0; case kDoubleAligned: case kDoubleUnaligned: return kDoubleSize - kTaggedSize; default: UNREACHABLE(); } return 0; } // static int Heap::GetFillToAlign(Address address, AllocationAlignment alignment) { if (alignment == kDoubleAligned && (address & kDoubleAlignmentMask) != 0) return kTaggedSize; if (alignment == kDoubleUnaligned && (address & kDoubleAlignmentMask) == 0) return kDoubleSize - kTaggedSize; // No fill if double is always aligned. return 0; } size_t Heap::GetCodeRangeReservedAreaSize() { return kReservedCodeRangePages * MemoryAllocator::GetCommitPageSize(); } // static HeapObject Heap::PrecedeWithFiller(ReadOnlyRoots roots, HeapObject object, int filler_size) { CreateFillerObjectAt(roots, object.address(), filler_size, ClearFreedMemoryMode::kDontClearFreedMemory); return HeapObject::FromAddress(object.address() + filler_size); } // static HeapObject Heap::AlignWithFiller(ReadOnlyRoots roots, HeapObject object, int object_size, int allocation_size, AllocationAlignment alignment) { int filler_size = allocation_size - object_size; DCHECK_LT(0, filler_size); int pre_filler = GetFillToAlign(object.address(), alignment); if (pre_filler) { object = PrecedeWithFiller(roots, object, pre_filler); filler_size -= pre_filler; } if (filler_size) { CreateFillerObjectAt(roots, object.address() + object_size, filler_size, ClearFreedMemoryMode::kDontClearFreedMemory); } return object; } void* Heap::AllocateExternalBackingStore( const std::function<void*(size_t)>& allocate, size_t byte_length) { if (!always_allocate()) { size_t new_space_backing_store_bytes = new_space()->ExternalBackingStoreBytes(); if (new_space_backing_store_bytes >= 2 * kMaxSemiSpaceSize && new_space_backing_store_bytes >= byte_length) { // Performing a young generation GC amortizes over the allocated backing // store bytes and may free enough external bytes for this allocation. CollectGarbage(NEW_SPACE, GarbageCollectionReason::kExternalMemoryPressure); } } // TODO(ulan): Perform GCs proactively based on the byte_length and // the current external backing store counters. void* result = allocate(byte_length); if (result) return result; if (!always_allocate()) { for (int i = 0; i < 2; i++) { CollectGarbage(OLD_SPACE, GarbageCollectionReason::kExternalMemoryPressure); result = allocate(byte_length); if (result) return result; } isolate()->counters()->gc_last_resort_from_handles()->Increment(); CollectAllAvailableGarbage( GarbageCollectionReason::kExternalMemoryPressure); } return allocate(byte_length); } void Heap::RegisterBackingStore(JSArrayBuffer buffer, std::shared_ptr<BackingStore> backing_store) { ArrayBufferTracker::RegisterNew(this, buffer, std::move(backing_store)); } std::shared_ptr<BackingStore> Heap::UnregisterBackingStore( JSArrayBuffer buffer) { return ArrayBufferTracker::Unregister(this, buffer); } std::shared_ptr<BackingStore> Heap::LookupBackingStore(JSArrayBuffer buffer) { return ArrayBufferTracker::Lookup(this, buffer); } void Heap::ConfigureInitialOldGenerationSize() { if (!old_generation_size_configured_ && tracer()->SurvivalEventsRecorded()) { const size_t minimum_growing_step = MemoryController<V8HeapTrait>::MinimumAllocationLimitGrowingStep( CurrentHeapGrowingMode()); const size_t new_old_generation_allocation_limit = Max(OldGenerationSizeOfObjects() + minimum_growing_step, static_cast<size_t>( static_cast<double>(old_generation_allocation_limit_) * (tracer()->AverageSurvivalRatio() / 100))); if (new_old_generation_allocation_limit < old_generation_allocation_limit_) { old_generation_allocation_limit_ = new_old_generation_allocation_limit; } else { old_generation_size_configured_ = true; } if (UseGlobalMemoryScheduling()) { const size_t new_global_memory_limit = Max( GlobalSizeOfObjects() + minimum_growing_step, static_cast<size_t>(static_cast<double>(global_allocation_limit_) * (tracer()->AverageSurvivalRatio() / 100))); if (new_global_memory_limit < global_allocation_limit_) { global_allocation_limit_ = new_global_memory_limit; } } } } void Heap::FlushNumberStringCache() { // Flush the number to string cache. int len = number_string_cache().length(); for (int i = 0; i < len; i++) { number_string_cache().set_undefined(i); } } namespace { HeapObject CreateFillerObjectAtImpl(ReadOnlyRoots roots, Address addr, int size, ClearFreedMemoryMode clear_memory_mode) { if (size == 0) return HeapObject(); HeapObject filler = HeapObject::FromAddress(addr); if (size == kTaggedSize) { filler.set_map_after_allocation(roots.unchecked_one_pointer_filler_map(), SKIP_WRITE_BARRIER); } else if (size == 2 * kTaggedSize) { filler.set_map_after_allocation(roots.unchecked_two_pointer_filler_map(), SKIP_WRITE_BARRIER); if (clear_memory_mode == ClearFreedMemoryMode::kClearFreedMemory) { AtomicSlot slot(ObjectSlot(addr) + 1); *slot = static_cast<Tagged_t>(kClearedFreeMemoryValue); } } else { DCHECK_GT(size, 2 * kTaggedSize); filler.set_map_after_allocation(roots.unchecked_free_space_map(), SKIP_WRITE_BARRIER); FreeSpace::cast(filler).relaxed_write_size(size); if (clear_memory_mode == ClearFreedMemoryMode::kClearFreedMemory) { MemsetTagged(ObjectSlot(addr) + 2, Object(kClearedFreeMemoryValue), (size / kTaggedSize) - 2); } } // At this point, we may be deserializing the heap from a snapshot, and // none of the maps have been created yet and are nullptr. DCHECK((filler.map_slot().contains_value(kNullAddress) && !Heap::FromWritableHeapObject(filler)->deserialization_complete()) || filler.map().IsMap()); return filler; } #ifdef DEBUG void VerifyNoNeedToClearSlots(Address start, Address end) { BasicMemoryChunk* basic_chunk = BasicMemoryChunk::FromAddress(start); if (basic_chunk->InReadOnlySpace()) return; MemoryChunk* chunk = static_cast<MemoryChunk*>(basic_chunk); // TODO(ulan): Support verification of large pages. if (chunk->InYoungGeneration() || chunk->IsLargePage()) return; BaseSpace* space = chunk->owner(); if (static_cast<PagedSpace*>(space)->is_off_thread_space()) return; space->heap()->VerifySlotRangeHasNoRecordedSlots(start, end); } #else void VerifyNoNeedToClearSlots(Address start, Address end) {} #endif // DEBUG } // namespace // static HeapObject Heap::CreateFillerObjectAt(ReadOnlyRoots roots, Address addr, int size, ClearFreedMemoryMode clear_memory_mode) { // TODO(leszeks): Verify that no slots need to be recorded. HeapObject filler = CreateFillerObjectAtImpl(roots, addr, size, clear_memory_mode); VerifyNoNeedToClearSlots(addr, addr + size); return filler; } void Heap::CreateFillerObjectAtBackground( Address addr, int size, ClearFreedMemoryMode clear_memory_mode) { CreateFillerObjectAtImpl(ReadOnlyRoots(this), addr, size, clear_memory_mode); // Do not verify whether slots are cleared here: the concurrent sweeper is not // allowed to access the main thread's remembered set. } HeapObject Heap::CreateFillerObjectAt(Address addr, int size, ClearRecordedSlots clear_slots_mode) { if (size == 0) return HeapObject(); HeapObject filler = CreateFillerObjectAtImpl( ReadOnlyRoots(this), addr, size, clear_slots_mode == ClearRecordedSlots::kYes ? ClearFreedMemoryMode::kClearFreedMemory : ClearFreedMemoryMode::kDontClearFreedMemory); if (!V8_ENABLE_THIRD_PARTY_HEAP_BOOL) { if (clear_slots_mode == ClearRecordedSlots::kYes) { ClearRecordedSlotRange(addr, addr + size); } else { VerifyNoNeedToClearSlots(addr, addr + size); } } return filler; } bool Heap::CanMoveObjectStart(HeapObject object) { if (!FLAG_move_object_start) return false; // Sampling heap profiler may have a reference to the object. if (isolate()->heap_profiler()->is_sampling_allocations()) return false; if (IsLargeObject(object)) return false; // We can move the object start if the page was already swept. return Page::FromHeapObject(object)->SweepingDone(); } // static bool Heap::InOffThreadSpace(HeapObject heap_object) { #ifdef V8_ENABLE_THIRD_PARTY_HEAP return false; // currently unsupported #else BaseSpace* owner = BasicMemoryChunk::FromHeapObject(heap_object)->owner(); if (owner->identity() == OLD_SPACE) { // TODO(leszeks): Should we exclude compaction spaces here? return static_cast<PagedSpace*>(owner)->is_off_thread_space(); } if (owner->identity() == LO_SPACE) { return static_cast<LargeObjectSpace*>(owner)->is_off_thread(); } return false; #endif } bool Heap::IsImmovable(HeapObject object) { if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) { // TODO(steveblackburn): For now all objects are immovable. // Will need to revisit once moving is supported. return true; } BasicMemoryChunk* chunk = BasicMemoryChunk::FromHeapObject(object); return chunk->NeverEvacuate() || IsLargeObject(object); } bool Heap::IsLargeObject(HeapObject object) { return BasicMemoryChunk::FromHeapObject(object)->IsLargePage(); } #ifdef ENABLE_SLOW_DCHECKS namespace { class LeftTrimmerVerifierRootVisitor : public RootVisitor { public: explicit LeftTrimmerVerifierRootVisitor(FixedArrayBase to_check) : to_check_(to_check) {} void VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) override { for (FullObjectSlot p = start; p < end; ++p) { DCHECK_NE(*p, to_check_); } } private: FixedArrayBase to_check_; DISALLOW_COPY_AND_ASSIGN(LeftTrimmerVerifierRootVisitor); }; } // namespace #endif // ENABLE_SLOW_DCHECKS namespace { bool MayContainRecordedSlots(HeapObject object) { // New space object do not have recorded slots. if (BasicMemoryChunk::FromHeapObject(object)->InYoungGeneration()) return false; // Allowlist objects that definitely do not have pointers. if (object.IsByteArray() || object.IsFixedDoubleArray()) return false; // Conservatively return true for other objects. return true; } } // namespace void Heap::OnMoveEvent(HeapObject target, HeapObject source, int size_in_bytes) { HeapProfiler* heap_profiler = isolate_->heap_profiler(); if (heap_profiler->is_tracking_object_moves()) { heap_profiler->ObjectMoveEvent(source.address(), target.address(), size_in_bytes); } for (auto& tracker : allocation_trackers_) { tracker->MoveEvent(source.address(), target.address(), size_in_bytes); } if (target.IsSharedFunctionInfo()) { LOG_CODE_EVENT(isolate_, SharedFunctionInfoMoveEvent(source.address(), target.address())); } else if (target.IsNativeContext()) { PROFILE(isolate_, NativeContextMoveEvent(source.address(), target.address())); } if (FLAG_verify_predictable) { ++allocations_count_; // Advance synthetic time by making a time request. MonotonicallyIncreasingTimeInMs(); UpdateAllocationsHash(source); UpdateAllocationsHash(target); UpdateAllocationsHash(size_in_bytes); if (allocations_count_ % FLAG_dump_allocations_digest_at_alloc == 0) { PrintAllocationsHash(); } } else if (FLAG_fuzzer_gc_analysis) { ++allocations_count_; } } FixedArrayBase Heap::LeftTrimFixedArray(FixedArrayBase object, int elements_to_trim) { if (elements_to_trim == 0) { // This simplifies reasoning in the rest of the function. return object; } CHECK(!object.is_null()); DCHECK(CanMoveObjectStart(object)); // Add custom visitor to concurrent marker if new left-trimmable type // is added. DCHECK(object.IsFixedArray() || object.IsFixedDoubleArray()); const int element_size = object.IsFixedArray() ? kTaggedSize : kDoubleSize; const int bytes_to_trim = elements_to_trim * element_size; Map map = object.map(); // For now this trick is only applied to fixed arrays which may be in new // space or old space. In a large object space the object's start must // coincide with chunk and thus the trick is just not applicable. DCHECK(!IsLargeObject(object)); DCHECK(object.map() != ReadOnlyRoots(this).fixed_cow_array_map()); STATIC_ASSERT(FixedArrayBase::kMapOffset == 0); STATIC_ASSERT(FixedArrayBase::kLengthOffset == kTaggedSize); STATIC_ASSERT(FixedArrayBase::kHeaderSize == 2 * kTaggedSize); const int len = object.length(); DCHECK(elements_to_trim <= len); // Calculate location of new array start. Address old_start = object.address(); Address new_start = old_start + bytes_to_trim; if (incremental_marking()->IsMarking()) { incremental_marking()->NotifyLeftTrimming( object, HeapObject::FromAddress(new_start)); } #ifdef DEBUG if (MayContainRecordedSlots(object)) { MemoryChunk* chunk = MemoryChunk::FromHeapObject(object); DCHECK(!chunk->RegisteredObjectWithInvalidatedSlots<OLD_TO_OLD>(object)); DCHECK(!chunk->RegisteredObjectWithInvalidatedSlots<OLD_TO_NEW>(object)); } #endif // Technically in new space this write might be omitted (except for // debug mode which iterates through the heap), but to play safer // we still do it. CreateFillerObjectAt(old_start, bytes_to_trim, MayContainRecordedSlots(object) ? ClearRecordedSlots::kYes : ClearRecordedSlots::kNo); // Initialize header of the trimmed array. Since left trimming is only // performed on pages which are not concurrently swept creating a filler // object does not require synchronization. RELAXED_WRITE_FIELD(object, bytes_to_trim, map); RELAXED_WRITE_FIELD(object, bytes_to_trim + kTaggedSize, Smi::FromInt(len - elements_to_trim)); FixedArrayBase new_object = FixedArrayBase::cast(HeapObject::FromAddress(new_start)); // Notify the heap profiler of change in object layout. OnMoveEvent(new_object, object, new_object.Size()); #ifdef ENABLE_SLOW_DCHECKS if (FLAG_enable_slow_asserts) { // Make sure the stack or other roots (e.g., Handles) don't contain pointers // to the original FixedArray (which is now the filler object). SafepointScope scope(this); LeftTrimmerVerifierRootVisitor root_visitor(object); ReadOnlyRoots(this).Iterate(&root_visitor); IterateRoots(&root_visitor, {}); } #endif // ENABLE_SLOW_DCHECKS return new_object; } void Heap::RightTrimFixedArray(FixedArrayBase object, int elements_to_trim) { const int len = object.length(); DCHECK_LE(elements_to_trim, len); DCHECK_GE(elements_to_trim, 0); int bytes_to_trim; if (object.IsByteArray()) { int new_size = ByteArray::SizeFor(len - elements_to_trim); bytes_to_trim = ByteArray::SizeFor(len) - new_size; DCHECK_GE(bytes_to_trim, 0); } else if (object.IsFixedArray()) { CHECK_NE(elements_to_trim, len); bytes_to_trim = elements_to_trim * kTaggedSize; } else { DCHECK(object.IsFixedDoubleArray()); CHECK_NE(elements_to_trim, len); bytes_to_trim = elements_to_trim * kDoubleSize; } CreateFillerForArray<FixedArrayBase>(object, elements_to_trim, bytes_to_trim); } void Heap::RightTrimWeakFixedArray(WeakFixedArray object, int elements_to_trim) { // This function is safe to use only at the end of the mark compact // collection: When marking, we record the weak slots, and shrinking // invalidates them. DCHECK_EQ(gc_state(), MARK_COMPACT); CreateFillerForArray<WeakFixedArray>(object, elements_to_trim, elements_to_trim * kTaggedSize); } template <typename T> void Heap::CreateFillerForArray(T object, int elements_to_trim, int bytes_to_trim) { DCHECK(object.IsFixedArrayBase() || object.IsByteArray() || object.IsWeakFixedArray()); // For now this trick is only applied to objects in new and paged space. DCHECK(object.map() != ReadOnlyRoots(this).fixed_cow_array_map()); if (bytes_to_trim == 0) { DCHECK_EQ(elements_to_trim, 0); // No need to create filler and update live bytes counters. return; } // Calculate location of new array end. int old_size = object.Size(); Address old_end = object.address() + old_size; Address new_end = old_end - bytes_to_trim; #ifdef DEBUG if (MayContainRecordedSlots(object)) { MemoryChunk* chunk = MemoryChunk::FromHeapObject(object); DCHECK(!chunk->RegisteredObjectWithInvalidatedSlots<OLD_TO_NEW>(object)); DCHECK(!chunk->RegisteredObjectWithInvalidatedSlots<OLD_TO_OLD>(object)); } #endif bool clear_slots = MayContainRecordedSlots(object); // Technically in new space this write might be omitted (except for // debug mode which iterates through the heap), but to play safer // we still do it. // We do not create a filler for objects in a large object space. if (!IsLargeObject(object)) { HeapObject filler = CreateFillerObjectAt( new_end, bytes_to_trim, clear_slots ? ClearRecordedSlots::kYes : ClearRecordedSlots::kNo); DCHECK(!filler.is_null()); // Clear the mark bits of the black area that belongs now to the filler. // This is an optimization. The sweeper will release black fillers anyway. if (incremental_marking()->black_allocation() && incremental_marking()->marking_state()->IsBlackOrGrey(filler)) { Page* page = Page::FromAddress(new_end); incremental_marking()->marking_state()->bitmap(page)->ClearRange( page->AddressToMarkbitIndex(new_end), page->AddressToMarkbitIndex(new_end + bytes_to_trim)); } } else if (clear_slots) { // Large objects are not swept, so it is not necessary to clear the // recorded slot. MemsetTagged(ObjectSlot(new_end), Object(kClearedFreeMemoryValue), (old_end - new_end) / kTaggedSize); } // Initialize header of the trimmed array. We are storing the new length // using release store after creating a filler for the left-over space to // avoid races with the sweeper thread. object.synchronized_set_length(object.length() - elements_to_trim); // Notify the heap object allocation tracker of change in object layout. The // array may not be moved during GC, and size has to be adjusted nevertheless. for (auto& tracker : allocation_trackers_) { tracker->UpdateObjectSizeEvent(object.address(), object.Size()); } } void Heap::MakeHeapIterable() { mark_compact_collector()->EnsureSweepingCompleted(); MakeLocalHeapLabsIterable(); } void Heap::MakeLocalHeapLabsIterable() { if (!FLAG_local_heaps) return; safepoint()->IterateLocalHeaps([](LocalHeap* local_heap) { local_heap->MakeLinearAllocationAreaIterable(); }); } namespace { double ComputeMutatorUtilizationImpl(double mutator_speed, double gc_speed) { constexpr double kMinMutatorUtilization = 0.0; constexpr double kConservativeGcSpeedInBytesPerMillisecond = 200000; if (mutator_speed == 0) return kMinMutatorUtilization; if (gc_speed == 0) gc_speed = kConservativeGcSpeedInBytesPerMillisecond; // Derivation: // mutator_utilization = mutator_time / (mutator_time + gc_time) // mutator_time = 1 / mutator_speed // gc_time = 1 / gc_speed // mutator_utilization = (1 / mutator_speed) / // (1 / mutator_speed + 1 / gc_speed) // mutator_utilization = gc_speed / (mutator_speed + gc_speed) return gc_speed / (mutator_speed + gc_speed); } } // namespace double Heap::ComputeMutatorUtilization(const char* tag, double mutator_speed, double gc_speed) { double result = ComputeMutatorUtilizationImpl(mutator_speed, gc_speed); if (FLAG_trace_mutator_utilization) { isolate()->PrintWithTimestamp( "%s mutator utilization = %.3f (" "mutator_speed=%.f, gc_speed=%.f)\n", tag, result, mutator_speed, gc_speed); } return result; } bool Heap::HasLowYoungGenerationAllocationRate() { double mu = ComputeMutatorUtilization( "Young generation", tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond(), tracer()->ScavengeSpeedInBytesPerMillisecond(kForSurvivedObjects)); constexpr double kHighMutatorUtilization = 0.993; return mu > kHighMutatorUtilization; } bool Heap::HasLowOldGenerationAllocationRate() { double mu = ComputeMutatorUtilization( "Old generation", tracer()->OldGenerationAllocationThroughputInBytesPerMillisecond(), tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond()); const double kHighMutatorUtilization = 0.993; return mu > kHighMutatorUtilization; } bool Heap::HasLowEmbedderAllocationRate() { if (!UseGlobalMemoryScheduling()) return true; DCHECK_NOT_NULL(local_embedder_heap_tracer()); double mu = ComputeMutatorUtilization( "Embedder", tracer()->CurrentEmbedderAllocationThroughputInBytesPerMillisecond(), tracer()->EmbedderSpeedInBytesPerMillisecond()); const double kHighMutatorUtilization = 0.993; return mu > kHighMutatorUtilization; } bool Heap::HasLowAllocationRate() { return HasLowYoungGenerationAllocationRate() && HasLowOldGenerationAllocationRate() && HasLowEmbedderAllocationRate(); } bool Heap::IsIneffectiveMarkCompact(size_t old_generation_size, double mutator_utilization) { const double kHighHeapPercentage = 0.8; const double kLowMutatorUtilization = 0.4; return old_generation_size >= kHighHeapPercentage * max_old_generation_size_ && mutator_utilization < kLowMutatorUtilization; } void Heap::CheckIneffectiveMarkCompact(size_t old_generation_size, double mutator_utilization) { const int kMaxConsecutiveIneffectiveMarkCompacts = 4; if (!FLAG_detect_ineffective_gcs_near_heap_limit) return; if (!IsIneffectiveMarkCompact(old_generation_size, mutator_utilization)) { consecutive_ineffective_mark_compacts_ = 0; return; } ++consecutive_ineffective_mark_compacts_; if (consecutive_ineffective_mark_compacts_ == kMaxConsecutiveIneffectiveMarkCompacts) { if (InvokeNearHeapLimitCallback()) { // The callback increased the heap limit. consecutive_ineffective_mark_compacts_ = 0; return; } FatalProcessOutOfMemory("Ineffective mark-compacts near heap limit"); } } bool Heap::HasHighFragmentation() { size_t used = OldGenerationSizeOfObjects(); size_t committed = CommittedOldGenerationMemory(); return HasHighFragmentation(used, committed); } bool Heap::HasHighFragmentation(size_t used, size_t committed) { const size_t kSlack = 16 * MB; // Fragmentation is high if committed > 2 * used + kSlack. // Rewrite the exression to avoid overflow. DCHECK_GE(committed, used); return committed - used > used + kSlack; } bool Heap::ShouldOptimizeForMemoryUsage() { const size_t kOldGenerationSlack = max_old_generation_size_ / 8; return FLAG_optimize_for_size || isolate()->IsIsolateInBackground() || isolate()->IsMemorySavingsModeActive() || HighMemoryPressure() || !CanExpandOldGeneration(kOldGenerationSlack); } void Heap::ActivateMemoryReducerIfNeeded() { // Activate memory reducer when switching to background if // - there was no mark compact since the start. // - the committed memory can be potentially reduced. // 2 pages for the old, code, and map space + 1 page for new space. const int kMinCommittedMemory = 7 * Page::kPageSize; if (ms_count_ == 0 && CommittedMemory() > kMinCommittedMemory && isolate()->IsIsolateInBackground()) { MemoryReducer::Event event; event.type = MemoryReducer::kPossibleGarbage; event.time_ms = MonotonicallyIncreasingTimeInMs(); memory_reducer_->NotifyPossibleGarbage(event); } } void Heap::ReduceNewSpaceSize() { // TODO(ulan): Unify this constant with the similar constant in // GCIdleTimeHandler once the change is merged to 4.5. static const size_t kLowAllocationThroughput = 1000; const double allocation_throughput = tracer()->CurrentAllocationThroughputInBytesPerMillisecond(); if (FLAG_predictable) return; if (ShouldReduceMemory() || ((allocation_throughput != 0) && (allocation_throughput < kLowAllocationThroughput))) { new_space_->Shrink(); new_lo_space_->SetCapacity(new_space_->Capacity()); UncommitFromSpace(); } } void Heap::FinalizeIncrementalMarkingIfComplete( GarbageCollectionReason gc_reason) { if (incremental_marking()->IsMarking() && (incremental_marking()->IsReadyToOverApproximateWeakClosure() || (!incremental_marking()->finalize_marking_completed() && mark_compact_collector()->marking_worklists()->IsEmpty() && local_embedder_heap_tracer()->ShouldFinalizeIncrementalMarking()))) { FinalizeIncrementalMarkingIncrementally(gc_reason); } else if (incremental_marking()->IsComplete() || (incremental_marking()->IsMarking() && mark_compact_collector()->marking_worklists()->IsEmpty() && local_embedder_heap_tracer() ->ShouldFinalizeIncrementalMarking())) { CollectAllGarbage(current_gc_flags_, gc_reason, current_gc_callback_flags_); } } void Heap::FinalizeIncrementalMarkingAtomically( GarbageCollectionReason gc_reason) { DCHECK(!incremental_marking()->IsStopped()); CollectAllGarbage(current_gc_flags_, gc_reason, current_gc_callback_flags_); } void Heap::InvokeIncrementalMarkingPrologueCallbacks() { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::MC_INCREMENTAL_EXTERNAL_PROLOGUE); VMState<EXTERNAL> state(isolate_); HandleScope handle_scope(isolate_); CallGCPrologueCallbacks(kGCTypeIncrementalMarking, kNoGCCallbackFlags); } } void Heap::InvokeIncrementalMarkingEpilogueCallbacks() { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::MC_INCREMENTAL_EXTERNAL_EPILOGUE); VMState<EXTERNAL> state(isolate_); HandleScope handle_scope(isolate_); CallGCEpilogueCallbacks(kGCTypeIncrementalMarking, kNoGCCallbackFlags); } } void Heap::FinalizeIncrementalMarkingIncrementally( GarbageCollectionReason gc_reason) { if (FLAG_trace_incremental_marking) { isolate()->PrintWithTimestamp( "[IncrementalMarking] (%s).\n", Heap::GarbageCollectionReasonToString(gc_reason)); } DevToolsTraceEventScope devtools_trace_event_scope( this, "MajorGC", "incremental finalization step"); HistogramTimerScope incremental_marking_scope( isolate()->counters()->gc_incremental_marking_finalize()); TRACE_EVENT0("v8", "V8.GCIncrementalMarkingFinalize"); TRACE_GC(tracer(), GCTracer::Scope::MC_INCREMENTAL_FINALIZE); SafepointScope safepoint(this); InvokeIncrementalMarkingPrologueCallbacks(); incremental_marking()->FinalizeIncrementally(); InvokeIncrementalMarkingEpilogueCallbacks(); } void Heap::RegisterDeserializedObjectsForBlackAllocation( Reservation* reservations, const std::vector<HeapObject>& large_objects, const std::vector<Address>& maps) { // TODO(ulan): pause black allocation during deserialization to avoid // iterating all these objects in one go. if (!incremental_marking()->black_allocation()) return; // Iterate black objects in old space, code space, map space, and large // object space for side effects. IncrementalMarking::MarkingState* marking_state = incremental_marking()->marking_state(); for (int i = OLD_SPACE; i < static_cast<int>(SnapshotSpace::kNumberOfHeapSpaces); i++) { const Heap::Reservation& res = reservations[i]; for (auto& chunk : res) { Address addr = chunk.start; while (addr < chunk.end) { HeapObject obj = HeapObject::FromAddress(addr); // Objects can have any color because incremental marking can // start in the middle of Heap::ReserveSpace(). if (marking_state->IsBlack(obj)) { incremental_marking()->ProcessBlackAllocatedObject(obj); } addr += obj.Size(); } } } // Large object space doesn't use reservations, so it needs custom handling. for (HeapObject object : large_objects) { incremental_marking()->ProcessBlackAllocatedObject(object); } // Map space doesn't use reservations, so it needs custom handling. for (Address addr : maps) { incremental_marking()->ProcessBlackAllocatedObject( HeapObject::FromAddress(addr)); } } void Heap::NotifyObjectLayoutChange( HeapObject object, const DisallowHeapAllocation&, InvalidateRecordedSlots invalidate_recorded_slots) { if (incremental_marking()->IsMarking()) { incremental_marking()->MarkBlackAndVisitObjectDueToLayoutChange(object); if (incremental_marking()->IsCompacting() && invalidate_recorded_slots == InvalidateRecordedSlots::kYes && MayContainRecordedSlots(object)) { MemoryChunk::FromHeapObject(object) ->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(object); } } if (invalidate_recorded_slots == InvalidateRecordedSlots::kYes && MayContainRecordedSlots(object)) { MemoryChunk::FromHeapObject(object) ->RegisterObjectWithInvalidatedSlots<OLD_TO_NEW>(object); } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { DCHECK(pending_layout_change_object_.is_null()); pending_layout_change_object_ = object; } #endif } #ifdef VERIFY_HEAP // Helper class for collecting slot addresses. class SlotCollectingVisitor final : public ObjectVisitor { public: void VisitPointers(HeapObject host, ObjectSlot start, ObjectSlot end) override { VisitPointers(host, MaybeObjectSlot(start), MaybeObjectSlot(end)); } void VisitPointers(HeapObject host, MaybeObjectSlot start, MaybeObjectSlot end) final { for (MaybeObjectSlot p = start; p < end; ++p) { slots_.push_back(p); } } void VisitCodeTarget(Code host, RelocInfo* rinfo) final { UNREACHABLE(); } void VisitEmbeddedPointer(Code host, RelocInfo* rinfo) override { UNREACHABLE(); } int number_of_slots() { return static_cast<int>(slots_.size()); } MaybeObjectSlot slot(int i) { return slots_[i]; } private: std::vector<MaybeObjectSlot> slots_; }; void Heap::VerifyObjectLayoutChange(HeapObject object, Map new_map) { if (!FLAG_verify_heap) return; // Check that Heap::NotifyObjectLayout was called for object transitions // that are not safe for concurrent marking. // If you see this check triggering for a freshly allocated object, // use object->set_map_after_allocation() to initialize its map. if (pending_layout_change_object_.is_null()) { if (object.IsJSObject()) { DCHECK(!object.map().TransitionRequiresSynchronizationWithGC(new_map)); } else { // Check that the set of slots before and after the transition match. SlotCollectingVisitor old_visitor; object.IterateFast(&old_visitor); MapWord old_map_word = object.map_word(); // Temporarily set the new map to iterate new slots. object.set_map_word(MapWord::FromMap(new_map)); SlotCollectingVisitor new_visitor; object.IterateFast(&new_visitor); // Restore the old map. object.set_map_word(old_map_word); DCHECK_EQ(new_visitor.number_of_slots(), old_visitor.number_of_slots()); for (int i = 0; i < new_visitor.number_of_slots(); i++) { DCHECK(new_visitor.slot(i) == old_visitor.slot(i)); } } } else { DCHECK_EQ(pending_layout_change_object_, object); pending_layout_change_object_ = HeapObject(); } } #endif GCIdleTimeHeapState Heap::ComputeHeapState() { GCIdleTimeHeapState heap_state; heap_state.contexts_disposed = contexts_disposed_; heap_state.contexts_disposal_rate = tracer()->ContextDisposalRateInMilliseconds(); heap_state.size_of_objects = static_cast<size_t>(SizeOfObjects()); heap_state.incremental_marking_stopped = incremental_marking()->IsStopped(); return heap_state; } bool Heap::PerformIdleTimeAction(GCIdleTimeAction action, GCIdleTimeHeapState heap_state, double deadline_in_ms) { bool result = false; switch (action) { case GCIdleTimeAction::kDone: result = true; break; case GCIdleTimeAction::kIncrementalStep: { incremental_marking()->AdvanceWithDeadline( deadline_in_ms, IncrementalMarking::NO_GC_VIA_STACK_GUARD, StepOrigin::kTask); FinalizeIncrementalMarkingIfComplete( GarbageCollectionReason::kFinalizeMarkingViaTask); result = incremental_marking()->IsStopped(); break; } case GCIdleTimeAction::kFullGC: { DCHECK_LT(0, contexts_disposed_); HistogramTimerScope scope(isolate_->counters()->gc_context()); TRACE_EVENT0("v8", "V8.GCContext"); CollectAllGarbage(kNoGCFlags, GarbageCollectionReason::kContextDisposal); break; } } return result; } void Heap::IdleNotificationEpilogue(GCIdleTimeAction action, GCIdleTimeHeapState heap_state, double start_ms, double deadline_in_ms) { double idle_time_in_ms = deadline_in_ms - start_ms; double current_time = MonotonicallyIncreasingTimeInMs(); last_idle_notification_time_ = current_time; double deadline_difference = deadline_in_ms - current_time; contexts_disposed_ = 0; if (FLAG_trace_idle_notification) { isolate_->PrintWithTimestamp( "Idle notification: requested idle time %.2f ms, used idle time %.2f " "ms, deadline usage %.2f ms [", idle_time_in_ms, idle_time_in_ms - deadline_difference, deadline_difference); switch (action) { case GCIdleTimeAction::kDone: PrintF("done"); break; case GCIdleTimeAction::kIncrementalStep: PrintF("incremental step"); break; case GCIdleTimeAction::kFullGC: PrintF("full GC"); break; } PrintF("]"); if (FLAG_trace_idle_notification_verbose) { PrintF("["); heap_state.Print(); PrintF("]"); } PrintF("\n"); } } double Heap::MonotonicallyIncreasingTimeInMs() { return V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() * static_cast<double>(base::Time::kMillisecondsPerSecond); } bool Heap::IdleNotification(int idle_time_in_ms) { return IdleNotification( V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() + (static_cast<double>(idle_time_in_ms) / static_cast<double>(base::Time::kMillisecondsPerSecond))); } bool Heap::IdleNotification(double deadline_in_seconds) { CHECK(HasBeenSetUp()); double deadline_in_ms = deadline_in_seconds * static_cast<double>(base::Time::kMillisecondsPerSecond); HistogramTimerScope idle_notification_scope( isolate_->counters()->gc_idle_notification()); TRACE_EVENT0("v8", "V8.GCIdleNotification"); double start_ms = MonotonicallyIncreasingTimeInMs(); double idle_time_in_ms = deadline_in_ms - start_ms; tracer()->SampleAllocation(start_ms, NewSpaceAllocationCounter(), OldGenerationAllocationCounter(), EmbedderAllocationCounter()); GCIdleTimeHeapState heap_state = ComputeHeapState(); GCIdleTimeAction action = gc_idle_time_handler_->Compute(idle_time_in_ms, heap_state); bool result = PerformIdleTimeAction(action, heap_state, deadline_in_ms); IdleNotificationEpilogue(action, heap_state, start_ms, deadline_in_ms); return result; } bool Heap::RecentIdleNotificationHappened() { return (last_idle_notification_time_ + GCIdleTimeHandler::kMaxScheduledIdleTime) > MonotonicallyIncreasingTimeInMs(); } class MemoryPressureInterruptTask : public CancelableTask { public: explicit MemoryPressureInterruptTask(Heap* heap) : CancelableTask(heap->isolate()), heap_(heap) {} ~MemoryPressureInterruptTask() override = default; private: // v8::internal::CancelableTask overrides. void RunInternal() override { heap_->CheckMemoryPressure(); } Heap* heap_; DISALLOW_COPY_AND_ASSIGN(MemoryPressureInterruptTask); }; void Heap::CheckMemoryPressure() { if (HighMemoryPressure()) { // The optimizing compiler may be unnecessarily holding on to memory. isolate()->AbortConcurrentOptimization(BlockingBehavior::kDontBlock); } MemoryPressureLevel memory_pressure_level = memory_pressure_level_; // Reset the memory pressure level to avoid recursive GCs triggered by // CheckMemoryPressure from AdjustAmountOfExternalMemory called by // the finalizers. memory_pressure_level_ = MemoryPressureLevel::kNone; if (memory_pressure_level == MemoryPressureLevel::kCritical) { TRACE_EVENT0("devtools.timeline,v8", "V8.CheckMemoryPressure"); CollectGarbageOnMemoryPressure(); } else if (memory_pressure_level == MemoryPressureLevel::kModerate) { if (FLAG_incremental_marking && incremental_marking()->IsStopped()) { TRACE_EVENT0("devtools.timeline,v8", "V8.CheckMemoryPressure"); StartIncrementalMarking(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure); } } } void Heap::CollectGarbageOnMemoryPressure() { const int kGarbageThresholdInBytes = 8 * MB; const double kGarbageThresholdAsFractionOfTotalMemory = 0.1; // This constant is the maximum response time in RAIL performance model. const double kMaxMemoryPressurePauseMs = 100; double start = MonotonicallyIncreasingTimeInMs(); CollectAllGarbage(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure, kGCCallbackFlagCollectAllAvailableGarbage); EagerlyFreeExternalMemory(); double end = MonotonicallyIncreasingTimeInMs(); // Estimate how much memory we can free. int64_t potential_garbage = (CommittedMemory() - SizeOfObjects()) + isolate()->isolate_data()->external_memory_; // If we can potentially free large amount of memory, then start GC right // away instead of waiting for memory reducer. if (potential_garbage >= kGarbageThresholdInBytes && potential_garbage >= CommittedMemory() * kGarbageThresholdAsFractionOfTotalMemory) { // If we spent less than half of the time budget, then perform full GC // Otherwise, start incremental marking. if (end - start < kMaxMemoryPressurePauseMs / 2) { CollectAllGarbage(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure, kGCCallbackFlagCollectAllAvailableGarbage); } else { if (FLAG_incremental_marking && incremental_marking()->IsStopped()) { StartIncrementalMarking(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure); } } } } void Heap::MemoryPressureNotification(MemoryPressureLevel level, bool is_isolate_locked) { TRACE_EVENT1("devtools.timeline,v8", "V8.MemoryPressureNotification", "level", static_cast<int>(level)); MemoryPressureLevel previous = memory_pressure_level_; memory_pressure_level_ = level; if ((previous != MemoryPressureLevel::kCritical && level == MemoryPressureLevel::kCritical) || (previous == MemoryPressureLevel::kNone && level == MemoryPressureLevel::kModerate)) { if (is_isolate_locked) { CheckMemoryPressure(); } else { ExecutionAccess access(isolate()); isolate()->stack_guard()->RequestGC(); auto taskrunner = V8::GetCurrentPlatform()->GetForegroundTaskRunner( reinterpret_cast<v8::Isolate*>(isolate())); taskrunner->PostTask(std::make_unique<MemoryPressureInterruptTask>(this)); } } } void Heap::EagerlyFreeExternalMemory() { if (FLAG_array_buffer_extension) { array_buffer_sweeper()->EnsureFinished(); } else { CHECK(!FLAG_local_heaps); for (Page* page : *old_space()) { if (!page->SweepingDone()) { base::MutexGuard guard(page->mutex()); if (!page->SweepingDone()) { ArrayBufferTracker::FreeDead( page, mark_compact_collector()->non_atomic_marking_state()); } } } } memory_allocator()->unmapper()->EnsureUnmappingCompleted(); } void Heap::AddNearHeapLimitCallback(v8::NearHeapLimitCallback callback, void* data) { const size_t kMaxCallbacks = 100; CHECK_LT(near_heap_limit_callbacks_.size(), kMaxCallbacks); for (auto callback_data : near_heap_limit_callbacks_) { CHECK_NE(callback_data.first, callback); } near_heap_limit_callbacks_.push_back(std::make_pair(callback, data)); } void Heap::RemoveNearHeapLimitCallback(v8::NearHeapLimitCallback callback, size_t heap_limit) { for (size_t i = 0; i < near_heap_limit_callbacks_.size(); i++) { if (near_heap_limit_callbacks_[i].first == callback) { near_heap_limit_callbacks_.erase(near_heap_limit_callbacks_.begin() + i); if (heap_limit) { RestoreHeapLimit(heap_limit); } return; } } UNREACHABLE(); } void Heap::AppendArrayBufferExtension(JSArrayBuffer object, ArrayBufferExtension* extension) { array_buffer_sweeper_->Append(object, extension); } void Heap::AutomaticallyRestoreInitialHeapLimit(double threshold_percent) { initial_max_old_generation_size_threshold_ = initial_max_old_generation_size_ * threshold_percent; } bool Heap::InvokeNearHeapLimitCallback() { if (near_heap_limit_callbacks_.size() > 0) { HandleScope scope(isolate()); v8::NearHeapLimitCallback callback = near_heap_limit_callbacks_.back().first; void* data = near_heap_limit_callbacks_.back().second; size_t heap_limit = callback(data, max_old_generation_size_, initial_max_old_generation_size_); if (heap_limit > max_old_generation_size_) { max_old_generation_size_ = Min(heap_limit, AllocatorLimitOnMaxOldGenerationSize()); return true; } } return false; } bool Heap::MeasureMemory(std::unique_ptr<v8::MeasureMemoryDelegate> delegate, v8::MeasureMemoryExecution execution) { HandleScope handle_scope(isolate()); std::vector<Handle<NativeContext>> contexts = FindAllNativeContexts(); std::vector<Handle<NativeContext>> to_measure; for (auto& current : contexts) { if (delegate->ShouldMeasure( v8::Utils::ToLocal(Handle<Context>::cast(current)))) { to_measure.push_back(current); } } return memory_measurement_->EnqueueRequest(std::move(delegate), execution, to_measure); } std::unique_ptr<v8::MeasureMemoryDelegate> Heap::MeasureMemoryDelegate( Handle<NativeContext> context, Handle<JSPromise> promise, v8::MeasureMemoryMode mode) { return i::MemoryMeasurement::DefaultDelegate(isolate_, context, promise, mode); } void Heap::CollectCodeStatistics() { TRACE_EVENT0("v8", "Heap::CollectCodeStatistics"); CodeStatistics::ResetCodeAndMetadataStatistics(isolate()); // We do not look for code in new space, or map space. If code // somehow ends up in those spaces, we would miss it here. CodeStatistics::CollectCodeStatistics(code_space_, isolate()); CodeStatistics::CollectCodeStatistics(old_space_, isolate()); CodeStatistics::CollectCodeStatistics(code_lo_space_, isolate()); } #ifdef DEBUG void Heap::Print() { if (!HasBeenSetUp()) return; isolate()->PrintStack(stdout); for (SpaceIterator it(this); it.HasNext();) { it.Next()->Print(); } } void Heap::ReportCodeStatistics(const char* title) { PrintF(">>>>>> Code Stats (%s) >>>>>>\n", title); CollectCodeStatistics(); CodeStatistics::ReportCodeStatistics(isolate()); } #endif // DEBUG const char* Heap::GarbageCollectionReasonToString( GarbageCollectionReason gc_reason) { switch (gc_reason) { case GarbageCollectionReason::kAllocationFailure: return "allocation failure"; case GarbageCollectionReason::kAllocationLimit: return "allocation limit"; case GarbageCollectionReason::kContextDisposal: return "context disposal"; case GarbageCollectionReason::kCountersExtension: return "counters extension"; case GarbageCollectionReason::kDebugger: return "debugger"; case GarbageCollectionReason::kDeserializer: return "deserialize"; case GarbageCollectionReason::kExternalMemoryPressure: return "external memory pressure"; case GarbageCollectionReason::kFinalizeMarkingViaStackGuard: return "finalize incremental marking via stack guard"; case GarbageCollectionReason::kFinalizeMarkingViaTask: return "finalize incremental marking via task"; case GarbageCollectionReason::kFullHashtable: return "full hash-table"; case GarbageCollectionReason::kHeapProfiler: return "heap profiler"; case GarbageCollectionReason::kTask: return "task"; case GarbageCollectionReason::kLastResort: return "last resort"; case GarbageCollectionReason::kLowMemoryNotification: return "low memory notification"; case GarbageCollectionReason::kMakeHeapIterable: return "make heap iterable"; case GarbageCollectionReason::kMemoryPressure: return "memory pressure"; case GarbageCollectionReason::kMemoryReducer: return "memory reducer"; case GarbageCollectionReason::kRuntime: return "runtime"; case GarbageCollectionReason::kSamplingProfiler: return "sampling profiler"; case GarbageCollectionReason::kSnapshotCreator: return "snapshot creator"; case GarbageCollectionReason::kTesting: return "testing"; case GarbageCollectionReason::kExternalFinalize: return "external finalize"; case GarbageCollectionReason::kGlobalAllocationLimit: return "global allocation limit"; case GarbageCollectionReason::kMeasureMemory: return "measure memory"; case GarbageCollectionReason::kUnknown: return "unknown"; } UNREACHABLE(); } bool Heap::Contains(HeapObject value) const { if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) { return true; } if (ReadOnlyHeap::Contains(value)) { return false; } if (memory_allocator()->IsOutsideAllocatedSpace(value.address())) { return false; } return HasBeenSetUp() && (new_space_->ToSpaceContains(value) || old_space_->Contains(value) || code_space_->Contains(value) || map_space_->Contains(value) || lo_space_->Contains(value) || code_lo_space_->Contains(value) || new_lo_space_->Contains(value)); } bool Heap::InSpace(HeapObject value, AllocationSpace space) const { if (memory_allocator()->IsOutsideAllocatedSpace(value.address())) { return false; } if (!HasBeenSetUp()) return false; switch (space) { case NEW_SPACE: return new_space_->ToSpaceContains(value); case OLD_SPACE: return old_space_->Contains(value); case CODE_SPACE: return code_space_->Contains(value); case MAP_SPACE: return map_space_->Contains(value); case LO_SPACE: return lo_space_->Contains(value); case CODE_LO_SPACE: return code_lo_space_->Contains(value); case NEW_LO_SPACE: return new_lo_space_->Contains(value); case RO_SPACE: return ReadOnlyHeap::Contains(value); } UNREACHABLE(); } bool Heap::InSpaceSlow(Address addr, AllocationSpace space) const { if (memory_allocator()->IsOutsideAllocatedSpace(addr)) { return false; } if (!HasBeenSetUp()) return false; switch (space) { case NEW_SPACE: return new_space_->ToSpaceContainsSlow(addr); case OLD_SPACE: return old_space_->ContainsSlow(addr); case CODE_SPACE: return code_space_->ContainsSlow(addr); case MAP_SPACE: return map_space_->ContainsSlow(addr); case LO_SPACE: return lo_space_->ContainsSlow(addr); case CODE_LO_SPACE: return code_lo_space_->ContainsSlow(addr); case NEW_LO_SPACE: return new_lo_space_->ContainsSlow(addr); case RO_SPACE: return read_only_space_->ContainsSlow(addr); } UNREACHABLE(); } bool Heap::IsValidAllocationSpace(AllocationSpace space) { switch (space) { case NEW_SPACE: case OLD_SPACE: case CODE_SPACE: case MAP_SPACE: case LO_SPACE: case NEW_LO_SPACE: case CODE_LO_SPACE: case RO_SPACE: return true; default: return false; } } #ifdef VERIFY_HEAP void Heap::Verify() { CHECK(HasBeenSetUp()); SafepointScope safepoint_scope(this); HandleScope scope(isolate()); MakeLocalHeapLabsIterable(); // We have to wait here for the sweeper threads to have an iterable heap. mark_compact_collector()->EnsureSweepingCompleted(); array_buffer_sweeper()->EnsureFinished(); VerifyPointersVisitor visitor(this); IterateRoots(&visitor, {}); if (!isolate()->context().is_null() && !isolate()->normalized_map_cache()->IsUndefined(isolate())) { NormalizedMapCache::cast(*isolate()->normalized_map_cache()) .NormalizedMapCacheVerify(isolate()); } VerifySmisVisitor smis_visitor; IterateSmiRoots(&smis_visitor); new_space_->Verify(isolate()); old_space_->Verify(isolate(), &visitor); map_space_->Verify(isolate(), &visitor); VerifyPointersVisitor no_dirty_regions_visitor(this); code_space_->Verify(isolate(), &no_dirty_regions_visitor); lo_space_->Verify(isolate()); code_lo_space_->Verify(isolate()); new_lo_space_->Verify(isolate()); VerifyStringTable(isolate()); } void Heap::VerifyReadOnlyHeap() { CHECK(!read_only_space_->writable()); read_only_space_->Verify(isolate()); } class SlotVerifyingVisitor : public ObjectVisitor { public: SlotVerifyingVisitor(std::set<Address>* untyped, std::set<std::pair<SlotType, Address> >* typed) : untyped_(untyped), typed_(typed) {} virtual bool ShouldHaveBeenRecorded(HeapObject host, MaybeObject target) = 0; void VisitPointers(HeapObject host, ObjectSlot start, ObjectSlot end) override { #ifdef DEBUG for (ObjectSlot slot = start; slot < end; ++slot) { DCHECK(!HasWeakHeapObjectTag(*slot)); } #endif // DEBUG VisitPointers(host, MaybeObjectSlot(start), MaybeObjectSlot(end)); } void VisitPointers(HeapObject host, MaybeObjectSlot start, MaybeObjectSlot end) final { for (MaybeObjectSlot slot = start; slot < end; ++slot) { if (ShouldHaveBeenRecorded(host, *slot)) { CHECK_GT(untyped_->count(slot.address()), 0); } } } void VisitCodeTarget(Code host, RelocInfo* rinfo) override { Object target = Code::GetCodeFromTargetAddress(rinfo->target_address()); if (ShouldHaveBeenRecorded(host, MaybeObject::FromObject(target))) { CHECK( InTypedSet(CODE_TARGET_SLOT, rinfo->pc()) || (rinfo->IsInConstantPool() && InTypedSet(CODE_ENTRY_SLOT, rinfo->constant_pool_entry_address()))); } } void VisitEmbeddedPointer(Code host, RelocInfo* rinfo) override { Object target = rinfo->target_object(); if (ShouldHaveBeenRecorded(host, MaybeObject::FromObject(target))) { CHECK( InTypedSet(FULL_EMBEDDED_OBJECT_SLOT, rinfo->pc()) || InTypedSet(COMPRESSED_EMBEDDED_OBJECT_SLOT, rinfo->pc()) || (rinfo->IsInConstantPool() && InTypedSet(COMPRESSED_OBJECT_SLOT, rinfo->constant_pool_entry_address())) || (rinfo->IsInConstantPool() && InTypedSet(FULL_OBJECT_SLOT, rinfo->constant_pool_entry_address()))); } } protected: bool InUntypedSet(ObjectSlot slot) { return untyped_->count(slot.address()) > 0; } private: bool InTypedSet(SlotType type, Address slot) { return typed_->count(std::make_pair(type, slot)) > 0; } std::set<Address>* untyped_; std::set<std::pair<SlotType, Address> >* typed_; }; class OldToNewSlotVerifyingVisitor : public SlotVerifyingVisitor { public: OldToNewSlotVerifyingVisitor(std::set<Address>* untyped, std::set<std::pair<SlotType, Address>>* typed, EphemeronRememberedSet* ephemeron_remembered_set) : SlotVerifyingVisitor(untyped, typed), ephemeron_remembered_set_(ephemeron_remembered_set) {} bool ShouldHaveBeenRecorded(HeapObject host, MaybeObject target) override { DCHECK_IMPLIES(target->IsStrongOrWeak() && Heap::InYoungGeneration(target), Heap::InToPage(target)); return target->IsStrongOrWeak() && Heap::InYoungGeneration(target) && !Heap::InYoungGeneration(host); } void VisitEphemeron(HeapObject host, int index, ObjectSlot key, ObjectSlot target) override { VisitPointer(host, target); #ifdef ENABLE_MINOR_MC if (FLAG_minor_mc) return VisitPointer(host, target); #endif // Keys are handled separately and should never appear in this set. CHECK(!InUntypedSet(key)); Object k = *key; if (!ObjectInYoungGeneration(host) && ObjectInYoungGeneration(k)) { EphemeronHashTable table = EphemeronHashTable::cast(host); auto it = ephemeron_remembered_set_->find(table); CHECK(it != ephemeron_remembered_set_->end()); int slot_index = EphemeronHashTable::SlotToIndex(table.address(), key.address()); InternalIndex entry = EphemeronHashTable::IndexToEntry(slot_index); CHECK(it->second.find(entry.as_int()) != it->second.end()); } } private: EphemeronRememberedSet* ephemeron_remembered_set_; }; template <RememberedSetType direction> void CollectSlots(MemoryChunk* chunk, Address start, Address end, std::set<Address>* untyped, std::set<std::pair<SlotType, Address> >* typed) { RememberedSet<direction>::Iterate( chunk, [start, end, untyped](MaybeObjectSlot slot) { if (start <= slot.address() && slot.address() < end) { untyped->insert(slot.address()); } return KEEP_SLOT; }, SlotSet::FREE_EMPTY_BUCKETS); if (direction == OLD_TO_NEW) { CHECK(chunk->SweepingDone()); RememberedSetSweeping::Iterate( chunk, [start, end, untyped](MaybeObjectSlot slot) { if (start <= slot.address() && slot.address() < end) { untyped->insert(slot.address()); } return KEEP_SLOT; }, SlotSet::FREE_EMPTY_BUCKETS); } RememberedSet<direction>::IterateTyped( chunk, [=](SlotType type, Address slot) { if (start <= slot && slot < end) { typed->insert(std::make_pair(type, slot)); } return KEEP_SLOT; }); } void Heap::VerifyRememberedSetFor(HeapObject object) { MemoryChunk* chunk = MemoryChunk::FromHeapObject(object); DCHECK_IMPLIES(chunk->mutex() == nullptr, ReadOnlyHeap::Contains(object)); // In RO_SPACE chunk->mutex() may be nullptr, so just ignore it. base::LockGuard<base::Mutex, base::NullBehavior::kIgnoreIfNull> lock_guard( chunk->mutex()); Address start = object.address(); Address end = start + object.Size(); std::set<Address> old_to_new; std::set<std::pair<SlotType, Address> > typed_old_to_new; if (!InYoungGeneration(object)) { CollectSlots<OLD_TO_NEW>(chunk, start, end, &old_to_new, &typed_old_to_new); OldToNewSlotVerifyingVisitor visitor(&old_to_new, &typed_old_to_new, &this->ephemeron_remembered_set_); object.IterateBody(&visitor); } // TODO(ulan): Add old to old slot set verification once all weak objects // have their own instance types and slots are recorded for all weal fields. } #endif #ifdef DEBUG void Heap::VerifyCountersAfterSweeping() { MakeLocalHeapLabsIterable(); PagedSpaceIterator spaces(this); for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { space->VerifyCountersAfterSweeping(this); } } void Heap::VerifyCountersBeforeConcurrentSweeping() { PagedSpaceIterator spaces(this); for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { space->VerifyCountersBeforeConcurrentSweeping(); } } #endif void Heap::ZapFromSpace() { if (!new_space_->IsFromSpaceCommitted()) return; for (Page* page : PageRange(new_space_->from_space().first_page(), nullptr)) { memory_allocator()->ZapBlock(page->area_start(), page->HighWaterMark() - page->area_start(), ZapValue()); } } void Heap::ZapCodeObject(Address start_address, int size_in_bytes) { #ifdef DEBUG DCHECK(IsAligned(start_address, kIntSize)); for (int i = 0; i < size_in_bytes / kIntSize; i++) { Memory<int>(start_address + i * kIntSize) = kCodeZapValue; } #endif } // TODO(ishell): move builtin accessors out from Heap. Code Heap::builtin(int index) { DCHECK(Builtins::IsBuiltinId(index)); return Code::cast(Object(isolate()->builtins_table()[index])); } Address Heap::builtin_address(int index) { DCHECK(Builtins::IsBuiltinId(index) || index == Builtins::builtin_count); return reinterpret_cast<Address>(&isolate()->builtins_table()[index]); } void Heap::set_builtin(int index, Code builtin) { DCHECK(Builtins::IsBuiltinId(index)); DCHECK(Internals::HasHeapObjectTag(builtin.ptr())); // The given builtin may be completely uninitialized thus we cannot check its // type here. isolate()->builtins_table()[index] = builtin.ptr(); } void Heap::IterateWeakRoots(RootVisitor* v, base::EnumSet<SkipRoot> options) { DCHECK(!options.contains(SkipRoot::kWeak)); v->VisitRootPointer(Root::kStringTable, nullptr, FullObjectSlot(&roots_table()[RootIndex::kStringTable])); v->Synchronize(VisitorSynchronization::kStringTable); if (!options.contains(SkipRoot::kExternalStringTable) && !options.contains(SkipRoot::kUnserializable)) { // Scavenge collections have special processing for this. // Do not visit for serialization, since the external string table will // be populated from scratch upon deserialization. external_string_table_.IterateAll(v); } v->Synchronize(VisitorSynchronization::kExternalStringsTable); } void Heap::IterateSmiRoots(RootVisitor* v) { // Acquire execution access since we are going to read stack limit values. ExecutionAccess access(isolate()); v->VisitRootPointers(Root::kSmiRootList, nullptr, roots_table().smi_roots_begin(), roots_table().smi_roots_end()); v->Synchronize(VisitorSynchronization::kSmiRootList); } // We cannot avoid stale handles to left-trimmed objects, but can only make // sure all handles still needed are updated. Filter out a stale pointer // and clear the slot to allow post processing of handles (needed because // the sweeper might actually free the underlying page). class FixStaleLeftTrimmedHandlesVisitor : public RootVisitor { public: explicit FixStaleLeftTrimmedHandlesVisitor(Heap* heap) : heap_(heap) { USE(heap_); } void VisitRootPointer(Root root, const char* description, FullObjectSlot p) override { FixHandle(p); } void VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) override { for (FullObjectSlot p = start; p < end; ++p) FixHandle(p); } private: inline void FixHandle(FullObjectSlot p) { if (!(*p).IsHeapObject()) return; HeapObject current = HeapObject::cast(*p); const MapWord map_word = current.map_word(); if (!map_word.IsForwardingAddress() && current.IsFreeSpaceOrFiller()) { #ifdef DEBUG // We need to find a FixedArrayBase map after walking the fillers. while (current.IsFreeSpaceOrFiller()) { Address next = current.ptr(); if (current.map() == ReadOnlyRoots(heap_).one_pointer_filler_map()) { next += kTaggedSize; } else if (current.map() == ReadOnlyRoots(heap_).two_pointer_filler_map()) { next += 2 * kTaggedSize; } else { next += current.Size(); } current = HeapObject::cast(Object(next)); } DCHECK(current.IsFixedArrayBase()); #endif // DEBUG p.store(Smi::zero()); } } Heap* heap_; }; void Heap::IterateRoots(RootVisitor* v, base::EnumSet<SkipRoot> options) { v->VisitRootPointers(Root::kStrongRootList, nullptr, roots_table().strong_roots_begin(), roots_table().strong_roots_end()); v->Synchronize(VisitorSynchronization::kStrongRootList); isolate_->bootstrapper()->Iterate(v); v->Synchronize(VisitorSynchronization::kBootstrapper); Relocatable::Iterate(isolate_, v); v->Synchronize(VisitorSynchronization::kRelocatable); isolate_->debug()->Iterate(v); v->Synchronize(VisitorSynchronization::kDebug); isolate_->compilation_cache()->Iterate(v); v->Synchronize(VisitorSynchronization::kCompilationCache); if (!options.contains(SkipRoot::kOldGeneration)) { IterateBuiltins(v); v->Synchronize(VisitorSynchronization::kBuiltins); } // Iterate over pointers being held by inactive threads. isolate_->thread_manager()->Iterate(v); v->Synchronize(VisitorSynchronization::kThreadManager); // Visitors in this block only run when not serializing. These include: // // - Thread-local and stack. // - Handles. // - Microtasks. // - The startup object cache. // // When creating real startup snapshot, these areas are expected to be empty. // It is also possible to create a snapshot of a *running* isolate for testing // purposes. In this case, these areas are likely not empty and will simply be // skipped. // // The general guideline for adding visitors to this section vs. adding them // above is that non-transient heap state is always visited, transient heap // state is visited only when not serializing. if (!options.contains(SkipRoot::kUnserializable)) { if (!options.contains(SkipRoot::kGlobalHandles)) { if (options.contains(SkipRoot::kWeak)) { if (options.contains(SkipRoot::kOldGeneration)) { // Skip handles that are either weak or old. isolate_->global_handles()->IterateYoungStrongAndDependentRoots(v); } else { // Skip handles that are weak. isolate_->global_handles()->IterateStrongRoots(v); } } else { // Do not skip weak handles. if (options.contains(SkipRoot::kOldGeneration)) { // Skip handles that are old. isolate_->global_handles()->IterateAllYoungRoots(v); } else { // Do not skip any handles. isolate_->global_handles()->IterateAllRoots(v); } } } v->Synchronize(VisitorSynchronization::kGlobalHandles); if (!options.contains(SkipRoot::kStack)) { IterateStackRoots(v); v->Synchronize(VisitorSynchronization::kTop); } // Iterate over local handles in handle scopes. FixStaleLeftTrimmedHandlesVisitor left_trim_visitor(this); isolate_->handle_scope_implementer()->Iterate(&left_trim_visitor); isolate_->handle_scope_implementer()->Iterate(v); if (FLAG_local_heaps) { safepoint_->Iterate(&left_trim_visitor); safepoint_->Iterate(v); isolate_->persistent_handles_list()->Iterate(&left_trim_visitor); isolate_->persistent_handles_list()->Iterate(v); } isolate_->IterateDeferredHandles(&left_trim_visitor); isolate_->IterateDeferredHandles(v); v->Synchronize(VisitorSynchronization::kHandleScope); if (options.contains(SkipRoot::kOldGeneration)) { isolate_->eternal_handles()->IterateYoungRoots(v); } else { isolate_->eternal_handles()->IterateAllRoots(v); } v->Synchronize(VisitorSynchronization::kEternalHandles); // Iterate over pending Microtasks stored in MicrotaskQueues. MicrotaskQueue* default_microtask_queue = isolate_->default_microtask_queue(); if (default_microtask_queue) { MicrotaskQueue* microtask_queue = default_microtask_queue; do { microtask_queue->IterateMicrotasks(v); microtask_queue = microtask_queue->next(); } while (microtask_queue != default_microtask_queue); } // Iterate over other strong roots (currently only identity maps and // deoptimization entries). for (StrongRootsList* list = strong_roots_list_; list; list = list->next) { v->VisitRootPointers(Root::kStrongRoots, nullptr, list->start, list->end); } v->Synchronize(VisitorSynchronization::kStrongRoots); // Iterate over the startup object cache unless serializing or // deserializing. SerializerDeserializer::Iterate(isolate_, v); v->Synchronize(VisitorSynchronization::kStartupObjectCache); } if (!options.contains(SkipRoot::kWeak)) { IterateWeakRoots(v, options); } } void Heap::IterateWeakGlobalHandles(RootVisitor* v) { isolate_->global_handles()->IterateWeakRoots(v); } void Heap::IterateBuiltins(RootVisitor* v) { for (int i = 0; i < Builtins::builtin_count; i++) { v->VisitRootPointer(Root::kBuiltins, Builtins::name(i), FullObjectSlot(builtin_address(i))); } // The entry table doesn't need to be updated since all builtins are embedded. STATIC_ASSERT(Builtins::AllBuiltinsAreIsolateIndependent()); } void Heap::IterateStackRoots(RootVisitor* v) { isolate_->Iterate(v); isolate_->global_handles()->IterateStrongStackRoots(v); } namespace { size_t GlobalMemorySizeFromV8Size(size_t v8_size) { const size_t kGlobalMemoryToV8Ratio = 2; return Min(static_cast<uint64_t>(std::numeric_limits<size_t>::max()), static_cast<uint64_t>(v8_size) * kGlobalMemoryToV8Ratio); } } // anonymous namespace void Heap::ConfigureHeap(const v8::ResourceConstraints& constraints) { // Initialize max_semi_space_size_. { max_semi_space_size_ = 8 * (kSystemPointerSize / 4) * MB; if (constraints.max_young_generation_size_in_bytes() > 0) { max_semi_space_size_ = SemiSpaceSizeFromYoungGenerationSize( constraints.max_young_generation_size_in_bytes()); } if (FLAG_max_semi_space_size > 0) { max_semi_space_size_ = static_cast<size_t>(FLAG_max_semi_space_size) * MB; } else if (FLAG_max_heap_size > 0) { size_t max_heap_size = static_cast<size_t>(FLAG_max_heap_size) * MB; size_t young_generation_size, old_generation_size; if (FLAG_max_old_space_size > 0) { old_generation_size = static_cast<size_t>(FLAG_max_old_space_size) * MB; young_generation_size = max_heap_size > old_generation_size ? max_heap_size - old_generation_size : 0; } else { GenerationSizesFromHeapSize(max_heap_size, &young_generation_size, &old_generation_size); } max_semi_space_size_ = SemiSpaceSizeFromYoungGenerationSize(young_generation_size); } if (FLAG_stress_compaction) { // This will cause more frequent GCs when stressing. max_semi_space_size_ = MB; } // TODO(dinfuehr): Rounding to a power of 2 is not longer needed. Remove it. max_semi_space_size_ = static_cast<size_t>(base::bits::RoundUpToPowerOfTwo64( static_cast<uint64_t>(max_semi_space_size_))); max_semi_space_size_ = Max(max_semi_space_size_, kMinSemiSpaceSize); max_semi_space_size_ = RoundDown<Page::kPageSize>(max_semi_space_size_); } // Initialize max_old_generation_size_ and max_global_memory_. { max_old_generation_size_ = 700ul * (kSystemPointerSize / 4) * MB; if (constraints.max_old_generation_size_in_bytes() > 0) { max_old_generation_size_ = constraints.max_old_generation_size_in_bytes(); } if (FLAG_max_old_space_size > 0) { max_old_generation_size_ = static_cast<size_t>(FLAG_max_old_space_size) * MB; } else if (FLAG_max_heap_size > 0) { size_t max_heap_size = static_cast<size_t>(FLAG_max_heap_size) * MB; size_t young_generation_size = YoungGenerationSizeFromSemiSpaceSize(max_semi_space_size_); max_old_generation_size_ = max_heap_size > young_generation_size ? max_heap_size - young_generation_size : 0; } max_old_generation_size_ = Max(max_old_generation_size_, MinOldGenerationSize()); max_old_generation_size_ = Min(max_old_generation_size_, AllocatorLimitOnMaxOldGenerationSize()); max_old_generation_size_ = RoundDown<Page::kPageSize>(max_old_generation_size_); max_global_memory_size_ = GlobalMemorySizeFromV8Size(max_old_generation_size_); } CHECK_IMPLIES(FLAG_max_heap_size > 0, FLAG_max_semi_space_size == 0 || FLAG_max_old_space_size == 0); // Initialize initial_semispace_size_. { initial_semispace_size_ = kMinSemiSpaceSize; if (max_semi_space_size_ == kMaxSemiSpaceSize) { // Start with at least 1*MB semi-space on machines with a lot of memory. initial_semispace_size_ = Max(initial_semispace_size_, static_cast<size_t>(1 * MB)); } if (constraints.initial_young_generation_size_in_bytes() > 0) { initial_semispace_size_ = SemiSpaceSizeFromYoungGenerationSize( constraints.initial_young_generation_size_in_bytes()); } if (FLAG_initial_heap_size > 0) { size_t young_generation, old_generation; Heap::GenerationSizesFromHeapSize( static_cast<size_t>(FLAG_initial_heap_size) * MB, &young_generation, &old_generation); initial_semispace_size_ = SemiSpaceSizeFromYoungGenerationSize(young_generation); } if (FLAG_min_semi_space_size > 0) { initial_semispace_size_ = static_cast<size_t>(FLAG_min_semi_space_size) * MB; } initial_semispace_size_ = Min(initial_semispace_size_, max_semi_space_size_); initial_semispace_size_ = RoundDown<Page::kPageSize>(initial_semispace_size_); } if (FLAG_lazy_new_space_shrinking) { initial_semispace_size_ = max_semi_space_size_; } // Initialize initial_old_space_size_. { initial_old_generation_size_ = kMaxInitialOldGenerationSize; if (constraints.initial_old_generation_size_in_bytes() > 0) { initial_old_generation_size_ = constraints.initial_old_generation_size_in_bytes(); old_generation_size_configured_ = true; } if (FLAG_initial_heap_size > 0) { size_t initial_heap_size = static_cast<size_t>(FLAG_initial_heap_size) * MB; size_t young_generation_size = YoungGenerationSizeFromSemiSpaceSize(initial_semispace_size_); initial_old_generation_size_ = initial_heap_size > young_generation_size ? initial_heap_size - young_generation_size : 0; old_generation_size_configured_ = true; } if (FLAG_initial_old_space_size > 0) { initial_old_generation_size_ = static_cast<size_t>(FLAG_initial_old_space_size) * MB; old_generation_size_configured_ = true; } initial_old_generation_size_ = Min(initial_old_generation_size_, max_old_generation_size_ / 2); initial_old_generation_size_ = RoundDown<Page::kPageSize>(initial_old_generation_size_); } if (old_generation_size_configured_) { // If the embedder pre-configures the initial old generation size, // then allow V8 to skip full GCs below that threshold. min_old_generation_size_ = initial_old_generation_size_; min_global_memory_size_ = GlobalMemorySizeFromV8Size(min_old_generation_size_); } if (FLAG_semi_space_growth_factor < 2) { FLAG_semi_space_growth_factor = 2; } old_generation_allocation_limit_ = initial_old_generation_size_; global_allocation_limit_ = GlobalMemorySizeFromV8Size(old_generation_allocation_limit_); initial_max_old_generation_size_ = max_old_generation_size_; // We rely on being able to allocate new arrays in paged spaces. DCHECK(kMaxRegularHeapObjectSize >= (JSArray::kHeaderSize + FixedArray::SizeFor(JSArray::kInitialMaxFastElementArray) + AllocationMemento::kSize)); code_range_size_ = constraints.code_range_size_in_bytes(); configured_ = true; } void Heap::AddToRingBuffer(const char* string) { size_t first_part = Min(strlen(string), kTraceRingBufferSize - ring_buffer_end_); memcpy(trace_ring_buffer_ + ring_buffer_end_, string, first_part); ring_buffer_end_ += first_part; if (first_part < strlen(string)) { ring_buffer_full_ = true; size_t second_part = strlen(string) - first_part; memcpy(trace_ring_buffer_, string + first_part, second_part); ring_buffer_end_ = second_part; } } void Heap::GetFromRingBuffer(char* buffer) { size_t copied = 0; if (ring_buffer_full_) { copied = kTraceRingBufferSize - ring_buffer_end_; memcpy(buffer, trace_ring_buffer_ + ring_buffer_end_, copied); } memcpy(buffer + copied, trace_ring_buffer_, ring_buffer_end_); } void Heap::ConfigureHeapDefault() { v8::ResourceConstraints constraints; ConfigureHeap(constraints); } void Heap::RecordStats(HeapStats* stats, bool take_snapshot) { *stats->start_marker = HeapStats::kStartMarker; *stats->end_marker = HeapStats::kEndMarker; *stats->ro_space_size = read_only_space_->Size(); *stats->ro_space_capacity = read_only_space_->Capacity(); *stats->new_space_size = new_space_->Size(); *stats->new_space_capacity = new_space_->Capacity(); *stats->old_space_size = old_space_->SizeOfObjects(); *stats->old_space_capacity = old_space_->Capacity(); *stats->code_space_size = code_space_->SizeOfObjects(); *stats->code_space_capacity = code_space_->Capacity(); *stats->map_space_size = map_space_->SizeOfObjects(); *stats->map_space_capacity = map_space_->Capacity(); *stats->lo_space_size = lo_space_->Size(); *stats->code_lo_space_size = code_lo_space_->Size(); isolate_->global_handles()->RecordStats(stats); *stats->memory_allocator_size = memory_allocator()->Size(); *stats->memory_allocator_capacity = memory_allocator()->Size() + memory_allocator()->Available(); *stats->os_error = base::OS::GetLastError(); *stats->malloced_memory = isolate_->allocator()->GetCurrentMemoryUsage(); *stats->malloced_peak_memory = isolate_->allocator()->GetMaxMemoryUsage(); if (take_snapshot) { HeapObjectIterator iterator(this); for (HeapObject obj = iterator.Next(); !obj.is_null(); obj = iterator.Next()) { InstanceType type = obj.map().instance_type(); DCHECK(0 <= type && type <= LAST_TYPE); stats->objects_per_type[type]++; stats->size_per_type[type] += obj.Size(); } } if (stats->last_few_messages != nullptr) GetFromRingBuffer(stats->last_few_messages); } size_t Heap::OldGenerationSizeOfObjects() { PagedSpaceIterator spaces(this); size_t total = 0; for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { total += space->SizeOfObjects(); } return total + lo_space_->SizeOfObjects(); } size_t Heap::GlobalSizeOfObjects() { const size_t on_heap_size = OldGenerationSizeOfObjects(); const size_t embedder_size = local_embedder_heap_tracer() ? local_embedder_heap_tracer()->used_size() : 0; return on_heap_size + embedder_size; } uint64_t Heap::PromotedExternalMemorySize() { IsolateData* isolate_data = isolate()->isolate_data(); if (isolate_data->external_memory_ <= isolate_data->external_memory_low_since_mark_compact_) { return 0; } return static_cast<uint64_t>( isolate_data->external_memory_ - isolate_data->external_memory_low_since_mark_compact_); } bool Heap::AllocationLimitOvershotByLargeMargin() { // This guards against too eager finalization in small heaps. // The number is chosen based on v8.browsing_mobile on Nexus 7v2. constexpr size_t kMarginForSmallHeaps = 32u * MB; const size_t v8_overshoot = old_generation_allocation_limit_ < OldGenerationObjectsAndPromotedExternalMemorySize() ? OldGenerationObjectsAndPromotedExternalMemorySize() - old_generation_allocation_limit_ : 0; const size_t global_overshoot = global_allocation_limit_ < GlobalSizeOfObjects() ? GlobalSizeOfObjects() - global_allocation_limit_ : 0; // Bail out if the V8 and global sizes are still below their respective // limits. if (v8_overshoot == 0 && global_overshoot == 0) { return false; } // Overshoot margin is 50% of allocation limit or half-way to the max heap // with special handling of small heaps. const size_t v8_margin = Min(Max(old_generation_allocation_limit_ / 2, kMarginForSmallHeaps), (max_old_generation_size_ - old_generation_allocation_limit_) / 2); const size_t global_margin = Min(Max(global_allocation_limit_ / 2, kMarginForSmallHeaps), (max_global_memory_size_ - global_allocation_limit_) / 2); return v8_overshoot >= v8_margin || global_overshoot >= global_margin; } bool Heap::ShouldOptimizeForLoadTime() { return isolate()->rail_mode() == PERFORMANCE_LOAD && !AllocationLimitOvershotByLargeMargin() && MonotonicallyIncreasingTimeInMs() < isolate()->LoadStartTimeMs() + kMaxLoadTimeMs; } // This predicate is called when an old generation space cannot allocated from // the free list and is about to add a new page. Returning false will cause a // major GC. It happens when the old generation allocation limit is reached and // - either we need to optimize for memory usage, // - or the incremental marking is not in progress and we cannot start it. bool Heap::ShouldExpandOldGenerationOnSlowAllocation(LocalHeap* local_heap) { if (always_allocate() || OldGenerationSpaceAvailable() > 0) return true; // We reached the old generation allocation limit. // Ensure that retry of allocation on background thread succeeds if (IsRetryOfFailedAllocation(local_heap)) return true; if (ShouldOptimizeForMemoryUsage()) return false; if (ShouldOptimizeForLoadTime()) return true; if (incremental_marking()->NeedsFinalization()) { return !AllocationLimitOvershotByLargeMargin(); } if (incremental_marking()->IsStopped() && IncrementalMarkingLimitReached() == IncrementalMarkingLimit::kNoLimit) { // We cannot start incremental marking. return false; } return true; } bool Heap::IsRetryOfFailedAllocation(LocalHeap* local_heap) { if (!local_heap) return false; return local_heap->allocation_failed_; } void Heap::AlwaysAllocateAfterTearDownStarted() { always_allocate_scope_count_++; collection_barrier_.ShutdownRequested(); } Heap::HeapGrowingMode Heap::CurrentHeapGrowingMode() { if (ShouldReduceMemory() || FLAG_stress_compaction) { return Heap::HeapGrowingMode::kMinimal; } if (ShouldOptimizeForMemoryUsage()) { return Heap::HeapGrowingMode::kConservative; } if (memory_reducer()->ShouldGrowHeapSlowly()) { return Heap::HeapGrowingMode::kSlow; } return Heap::HeapGrowingMode::kDefault; } base::Optional<size_t> Heap::GlobalMemoryAvailable() { if (!UseGlobalMemoryScheduling()) return {}; size_t global_size = GlobalSizeOfObjects(); if (global_size < global_allocation_limit_) return global_allocation_limit_ - global_size; return 0; } double Heap::PercentToOldGenerationLimit() { double size_at_gc = old_generation_size_at_last_gc_; double size_now = OldGenerationObjectsAndPromotedExternalMemorySize(); double current_bytes = size_now - size_at_gc; double total_bytes = old_generation_allocation_limit_ - size_at_gc; return total_bytes > 0 ? (current_bytes / total_bytes) * 100.0 : 0; } double Heap::PercentToGlobalMemoryLimit() { double size_at_gc = old_generation_size_at_last_gc_; double size_now = OldGenerationObjectsAndPromotedExternalMemorySize(); double current_bytes = size_now - size_at_gc; double total_bytes = old_generation_allocation_limit_ - size_at_gc; return total_bytes > 0 ? (current_bytes / total_bytes) * 100.0 : 0; } // This function returns either kNoLimit, kSoftLimit, or kHardLimit. // The kNoLimit means that either incremental marking is disabled or it is too // early to start incremental marking. // The kSoftLimit means that incremental marking should be started soon. // The kHardLimit means that incremental marking should be started immediately. Heap::IncrementalMarkingLimit Heap::IncrementalMarkingLimitReached() { // Code using an AlwaysAllocateScope assumes that the GC state does not // change; that implies that no marking steps must be performed. if (!incremental_marking()->CanBeActivated() || always_allocate()) { // Incremental marking is disabled or it is too early to start. return IncrementalMarkingLimit::kNoLimit; } if (FLAG_stress_incremental_marking) { return IncrementalMarkingLimit::kHardLimit; } if (incremental_marking()->IsBelowActivationThresholds()) { // Incremental marking is disabled or it is too early to start. return IncrementalMarkingLimit::kNoLimit; } if ((FLAG_stress_compaction && (gc_count_ & 1) != 0) || HighMemoryPressure()) { // If there is high memory pressure or stress testing is enabled, then // start marking immediately. return IncrementalMarkingLimit::kHardLimit; } if (FLAG_stress_marking > 0) { int current_percent = static_cast<int>( std::max(PercentToOldGenerationLimit(), PercentToGlobalMemoryLimit())); if (current_percent > 0) { if (FLAG_trace_stress_marking) { isolate()->PrintWithTimestamp( "[IncrementalMarking] %d%% of the memory limit reached\n", current_percent); } if (FLAG_fuzzer_gc_analysis) { // Skips values >=100% since they already trigger marking. if (current_percent < 100) { max_marking_limit_reached_ = std::max<double>(max_marking_limit_reached_, current_percent); } } else if (current_percent >= stress_marking_percentage_) { stress_marking_percentage_ = NextStressMarkingLimit(); return IncrementalMarkingLimit::kHardLimit; } } } if (FLAG_incremental_marking_soft_trigger > 0 || FLAG_incremental_marking_hard_trigger > 0) { int current_percent = static_cast<int>( std::max(PercentToOldGenerationLimit(), PercentToGlobalMemoryLimit())); if (current_percent > FLAG_incremental_marking_hard_trigger && FLAG_incremental_marking_hard_trigger > 0) { return IncrementalMarkingLimit::kHardLimit; } if (current_percent > FLAG_incremental_marking_soft_trigger && FLAG_incremental_marking_soft_trigger > 0) { return IncrementalMarkingLimit::kSoftLimit; } return IncrementalMarkingLimit::kNoLimit; } size_t old_generation_space_available = OldGenerationSpaceAvailable(); const base::Optional<size_t> global_memory_available = GlobalMemoryAvailable(); if (old_generation_space_available > new_space_->Capacity() && (!global_memory_available || global_memory_available > new_space_->Capacity())) { return IncrementalMarkingLimit::kNoLimit; } if (ShouldOptimizeForMemoryUsage()) { return IncrementalMarkingLimit::kHardLimit; } if (ShouldOptimizeForLoadTime()) { return IncrementalMarkingLimit::kNoLimit; } if (old_generation_space_available == 0) { return IncrementalMarkingLimit::kHardLimit; } if (global_memory_available && *global_memory_available == 0) { return IncrementalMarkingLimit::kHardLimit; } return IncrementalMarkingLimit::kSoftLimit; } void Heap::EnableInlineAllocation() { if (!inline_allocation_disabled_) return; inline_allocation_disabled_ = false; // Update inline allocation limit for new space. new_space()->UpdateInlineAllocationLimit(0); } void Heap::DisableInlineAllocation() { if (inline_allocation_disabled_) return; inline_allocation_disabled_ = true; // Update inline allocation limit for new space. new_space()->UpdateInlineAllocationLimit(0); // Update inline allocation limit for old spaces. PagedSpaceIterator spaces(this); CodeSpaceMemoryModificationScope modification_scope(this); for (PagedSpace* space = spaces.Next(); space != nullptr; space = spaces.Next()) { space->FreeLinearAllocationArea(); } } HeapObject Heap::EnsureImmovableCode(HeapObject heap_object, int object_size) { // Code objects which should stay at a fixed address are allocated either // in the first page of code space, in large object space, or (during // snapshot creation) the containing page is marked as immovable. DCHECK(!heap_object.is_null()); #ifndef V8_ENABLE_THIRD_PARTY_HEAP DCHECK(code_space_->Contains(heap_object)); #endif DCHECK_GE(object_size, 0); if (!Heap::IsImmovable(heap_object)) { if (isolate()->serializer_enabled() || code_space_->first_page()->Contains(heap_object.address())) { BasicMemoryChunk::FromHeapObject(heap_object)->MarkNeverEvacuate(); } else { // Discard the first code allocation, which was on a page where it could // be moved. CreateFillerObjectAt(heap_object.address(), object_size, ClearRecordedSlots::kNo); heap_object = AllocateRawCodeInLargeObjectSpace(object_size); UnprotectAndRegisterMemoryChunk(heap_object); ZapCodeObject(heap_object.address(), object_size); OnAllocationEvent(heap_object, object_size); } } return heap_object; } HeapObject Heap::AllocateRawWithLightRetrySlowPath( int size, AllocationType allocation, AllocationOrigin origin, AllocationAlignment alignment) { HeapObject result; AllocationResult alloc = AllocateRaw(size, allocation, origin, alignment); if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // Two GCs before panicking. In newspace will almost always succeed. for (int i = 0; i < 2; i++) { CollectGarbage(alloc.RetrySpace(), GarbageCollectionReason::kAllocationFailure); alloc = AllocateRaw(size, allocation, origin, alignment); if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } } return HeapObject(); } HeapObject Heap::AllocateRawWithRetryOrFailSlowPath( int size, AllocationType allocation, AllocationOrigin origin, AllocationAlignment alignment) { AllocationResult alloc; HeapObject result = AllocateRawWithLightRetrySlowPath(size, allocation, origin, alignment); if (!result.is_null()) return result; isolate()->counters()->gc_last_resort_from_handles()->Increment(); CollectAllAvailableGarbage(GarbageCollectionReason::kLastResort); { AlwaysAllocateScope scope(this); alloc = AllocateRaw(size, allocation, origin, alignment); } if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // TODO(1181417): Fix this. FatalProcessOutOfMemory("CALL_AND_RETRY_LAST"); return HeapObject(); } // TODO(jkummerow): Refactor this. AllocateRaw should take an "immovability" // parameter and just do what's necessary. HeapObject Heap::AllocateRawCodeInLargeObjectSpace(int size) { AllocationResult alloc = code_lo_space()->AllocateRaw(size); HeapObject result; if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // Two GCs before panicking. for (int i = 0; i < 2; i++) { CollectGarbage(alloc.RetrySpace(), GarbageCollectionReason::kAllocationFailure); alloc = code_lo_space()->AllocateRaw(size); if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } } isolate()->counters()->gc_last_resort_from_handles()->Increment(); CollectAllAvailableGarbage(GarbageCollectionReason::kLastResort); { AlwaysAllocateScope scope(this); alloc = code_lo_space()->AllocateRaw(size); } if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // TODO(1181417): Fix this. FatalProcessOutOfMemory("CALL_AND_RETRY_LAST"); return HeapObject(); } void Heap::SetUp() { #ifdef V8_ENABLE_ALLOCATION_TIMEOUT allocation_timeout_ = NextAllocationTimeout(); #endif #ifdef V8_ENABLE_THIRD_PARTY_HEAP tp_heap_ = third_party_heap::Heap::New(isolate()); #endif // Initialize heap spaces and initial maps and objects. // // If the heap is not yet configured (e.g. through the API), configure it. // Configuration is based on the flags new-space-size (really the semispace // size) and old-space-size if set or the initial values of semispace_size_ // and old_generation_size_ otherwise. if (!configured_) ConfigureHeapDefault(); mmap_region_base_ = reinterpret_cast<uintptr_t>(v8::internal::GetRandomMmapAddr()) & ~kMmapRegionMask; // Set up memory allocator. memory_allocator_.reset( new MemoryAllocator(isolate_, MaxReserved(), code_range_size_)); mark_compact_collector_.reset(new MarkCompactCollector(this)); scavenger_collector_.reset(new ScavengerCollector(this)); incremental_marking_.reset( new IncrementalMarking(this, mark_compact_collector_->weak_objects())); if (FLAG_concurrent_marking || FLAG_parallel_marking) { concurrent_marking_.reset(new ConcurrentMarking( this, mark_compact_collector_->marking_worklists_holder(), mark_compact_collector_->weak_objects())); } else { concurrent_marking_.reset(new ConcurrentMarking(this, nullptr, nullptr)); } for (int i = FIRST_SPACE; i <= LAST_SPACE; i++) { space_[i] = nullptr; } } void Heap::SetUpFromReadOnlyHeap(ReadOnlyHeap* ro_heap) { DCHECK_NOT_NULL(ro_heap); DCHECK_IMPLIES(read_only_space_ != nullptr, read_only_space_ == ro_heap->read_only_space()); space_[RO_SPACE] = nullptr; read_only_space_ = ro_heap->read_only_space(); } void Heap::ReplaceReadOnlySpace(SharedReadOnlySpace* space) { CHECK(V8_SHARED_RO_HEAP_BOOL); delete read_only_space_; read_only_space_ = space; } void Heap::SetUpSpaces() { // Ensure SetUpFromReadOnlySpace has been ran. DCHECK_NOT_NULL(read_only_space_); space_[NEW_SPACE] = new_space_ = new NewSpace(this, memory_allocator_->data_page_allocator(), initial_semispace_size_, max_semi_space_size_); space_[OLD_SPACE] = old_space_ = new OldSpace(this); space_[CODE_SPACE] = code_space_ = new CodeSpace(this); space_[MAP_SPACE] = map_space_ = new MapSpace(this); space_[LO_SPACE] = lo_space_ = new OldLargeObjectSpace(this); space_[NEW_LO_SPACE] = new_lo_space_ = new NewLargeObjectSpace(this, new_space_->Capacity()); space_[CODE_LO_SPACE] = code_lo_space_ = new CodeLargeObjectSpace(this); for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount); i++) { deferred_counters_[i] = 0; } tracer_.reset(new GCTracer(this)); #ifdef ENABLE_MINOR_MC minor_mark_compact_collector_ = new MinorMarkCompactCollector(this); #else minor_mark_compact_collector_ = nullptr; #endif // ENABLE_MINOR_MC array_buffer_collector_.reset(new ArrayBufferCollector(this)); array_buffer_sweeper_.reset(new ArrayBufferSweeper(this)); gc_idle_time_handler_.reset(new GCIdleTimeHandler()); memory_measurement_.reset(new MemoryMeasurement(isolate())); memory_reducer_.reset(new MemoryReducer(this)); if (V8_UNLIKELY(TracingFlags::is_gc_stats_enabled())) { live_object_stats_.reset(new ObjectStats(this)); dead_object_stats_.reset(new ObjectStats(this)); } local_embedder_heap_tracer_.reset(new LocalEmbedderHeapTracer(isolate())); LOG(isolate_, IntPtrTEvent("heap-capacity", Capacity())); LOG(isolate_, IntPtrTEvent("heap-available", Available())); mark_compact_collector()->SetUp(); #ifdef ENABLE_MINOR_MC if (minor_mark_compact_collector() != nullptr) { minor_mark_compact_collector()->SetUp(); } #endif // ENABLE_MINOR_MC scavenge_job_.reset(new ScavengeJob()); scavenge_task_observer_.reset(new ScavengeTaskObserver( this, ScavengeJob::YoungGenerationTaskTriggerSize(this))); new_space()->AddAllocationObserver(scavenge_task_observer_.get()); SetGetExternallyAllocatedMemoryInBytesCallback( DefaultGetExternallyAllocatedMemoryInBytesCallback); if (FLAG_stress_marking > 0) { stress_marking_percentage_ = NextStressMarkingLimit(); stress_marking_observer_ = new StressMarkingObserver(this); AddAllocationObserversToAllSpaces(stress_marking_observer_, stress_marking_observer_); } if (FLAG_stress_scavenge > 0) { stress_scavenge_observer_ = new StressScavengeObserver(this); new_space()->AddAllocationObserver(stress_scavenge_observer_); } write_protect_code_memory_ = FLAG_write_protect_code_memory; } void Heap::InitializeHashSeed() { DCHECK(!deserialization_complete_); uint64_t new_hash_seed; if (FLAG_hash_seed == 0) { int64_t rnd = isolate()->random_number_generator()->NextInt64(); new_hash_seed = static_cast<uint64_t>(rnd); } else { new_hash_seed = static_cast<uint64_t>(FLAG_hash_seed); } ReadOnlyRoots(this).hash_seed().copy_in( 0, reinterpret_cast<byte*>(&new_hash_seed), kInt64Size); } int Heap::NextAllocationTimeout(int current_timeout) { if (FLAG_random_gc_interval > 0) { // If current timeout hasn't reached 0 the GC was caused by something // different than --stress-atomic-gc flag and we don't update the timeout. if (current_timeout <= 0) { return isolate()->fuzzer_rng()->NextInt(FLAG_random_gc_interval + 1); } else { return current_timeout; } } return FLAG_gc_interval; } void Heap::PrintAllocationsHash() { uint32_t hash = StringHasher::GetHashCore(raw_allocations_hash_); PrintF("\n### Allocations = %u, hash = 0x%08x\n", allocations_count(), hash); } void Heap::PrintMaxMarkingLimitReached() { PrintF("\n### Maximum marking limit reached = %.02lf\n", max_marking_limit_reached_); } void Heap::PrintMaxNewSpaceSizeReached() { PrintF("\n### Maximum new space size reached = %.02lf\n", stress_scavenge_observer_->MaxNewSpaceSizeReached()); } int Heap::NextStressMarkingLimit() { return isolate()->fuzzer_rng()->NextInt(FLAG_stress_marking + 1); } void Heap::NotifyDeserializationComplete() { PagedSpaceIterator spaces(this); for (PagedSpace* s = spaces.Next(); s != nullptr; s = spaces.Next()) { if (isolate()->snapshot_available()) s->ShrinkImmortalImmovablePages(); #ifdef DEBUG // All pages right after bootstrapping must be marked as never-evacuate. for (Page* p : *s) { DCHECK(p->NeverEvacuate()); } #endif // DEBUG } if (FLAG_stress_concurrent_allocation) { StressConcurrentAllocatorTask::Schedule(isolate()); } deserialization_complete_ = true; } void Heap::NotifyBootstrapComplete() { // This function is invoked for each native context creation. We are // interested only in the first native context. if (old_generation_capacity_after_bootstrap_ == 0) { old_generation_capacity_after_bootstrap_ = OldGenerationCapacity(); } } void Heap::NotifyOldGenerationExpansion(AllocationSpace space, MemoryChunk* chunk) { // Pages created during bootstrapping may contain immortal immovable objects. if (!deserialization_complete()) { chunk->MarkNeverEvacuate(); } if (space == CODE_SPACE || space == CODE_LO_SPACE) { isolate()->AddCodeMemoryChunk(chunk); } const size_t kMemoryReducerActivationThreshold = 1 * MB; if (old_generation_capacity_after_bootstrap_ && ms_count_ == 0 && OldGenerationCapacity() >= old_generation_capacity_after_bootstrap_ + kMemoryReducerActivationThreshold && FLAG_memory_reducer_for_small_heaps) { MemoryReducer::Event event; event.type = MemoryReducer::kPossibleGarbage; event.time_ms = MonotonicallyIncreasingTimeInMs(); memory_reducer()->NotifyPossibleGarbage(event); } } void Heap::SetEmbedderHeapTracer(EmbedderHeapTracer* tracer) { DCHECK_EQ(gc_state_, HeapState::NOT_IN_GC); local_embedder_heap_tracer()->SetRemoteTracer(tracer); } EmbedderHeapTracer* Heap::GetEmbedderHeapTracer() const { return local_embedder_heap_tracer()->remote_tracer(); } EmbedderHeapTracer::TraceFlags Heap::flags_for_embedder_tracer() const { if (is_current_gc_forced()) { return EmbedderHeapTracer::TraceFlags::kForced; } else if (ShouldReduceMemory()) { return EmbedderHeapTracer::TraceFlags::kReduceMemory; } return EmbedderHeapTracer::TraceFlags::kNoFlags; } void Heap::RegisterExternallyReferencedObject(Address* location) { GlobalHandles::MarkTraced(location); Object object(*location); if (!object.IsHeapObject()) { // The embedder is not aware of whether numbers are materialized as heap // objects are just passed around as Smis. return; } HeapObject heap_object = HeapObject::cast(object); DCHECK(IsValidHeapObject(this, heap_object)); if (FLAG_incremental_marking_wrappers && incremental_marking()->IsMarking()) { incremental_marking()->WhiteToGreyAndPush(heap_object); } else { DCHECK(mark_compact_collector()->in_use()); mark_compact_collector()->MarkExternallyReferencedObject(heap_object); } } void Heap::StartTearDown() { SetGCState(TEAR_DOWN); // Background threads may allocate and block until GC is performed. However // this might never happen when the main thread tries to quit and doesn't // process the event queue anymore. Avoid this deadlock by allowing all // allocations after tear down was requested to make sure all background // threads finish. AlwaysAllocateAfterTearDownStarted(); #ifdef VERIFY_HEAP // {StartTearDown} is called fairly early during Isolate teardown, so it's // a good time to run heap verification (if requested), before starting to // tear down parts of the Isolate. if (FLAG_verify_heap) { SafepointScope scope(this); Verify(); } #endif } void Heap::TearDown() { DCHECK_EQ(gc_state_, TEAR_DOWN); // It's too late for Heap::Verify() here, as parts of the Isolate are // already gone by the time this is called. UpdateMaximumCommitted(); if (FLAG_verify_predictable || FLAG_fuzzer_gc_analysis) { PrintAllocationsHash(); } if (FLAG_fuzzer_gc_analysis) { if (FLAG_stress_marking > 0) { PrintMaxMarkingLimitReached(); } if (FLAG_stress_scavenge > 0) { PrintMaxNewSpaceSizeReached(); } } new_space()->RemoveAllocationObserver(scavenge_task_observer_.get()); scavenge_task_observer_.reset(); scavenge_job_.reset(); if (FLAG_stress_marking > 0) { RemoveAllocationObserversFromAllSpaces(stress_marking_observer_, stress_marking_observer_); delete stress_marking_observer_; stress_marking_observer_ = nullptr; } if (FLAG_stress_scavenge > 0) { new_space()->RemoveAllocationObserver(stress_scavenge_observer_); delete stress_scavenge_observer_; stress_scavenge_observer_ = nullptr; } if (mark_compact_collector_) { mark_compact_collector_->TearDown(); mark_compact_collector_.reset(); } #ifdef ENABLE_MINOR_MC if (minor_mark_compact_collector_ != nullptr) { minor_mark_compact_collector_->TearDown(); delete minor_mark_compact_collector_; minor_mark_compact_collector_ = nullptr; } #endif // ENABLE_MINOR_MC scavenger_collector_.reset(); array_buffer_collector_.reset(); array_buffer_sweeper_.reset(); incremental_marking_.reset(); concurrent_marking_.reset(); gc_idle_time_handler_.reset(); memory_measurement_.reset(); if (memory_reducer_ != nullptr) { memory_reducer_->TearDown(); memory_reducer_.reset(); } live_object_stats_.reset(); dead_object_stats_.reset(); local_embedder_heap_tracer_.reset(); external_string_table_.TearDown(); // Tear down all ArrayBuffers before tearing down the heap since their // byte_length may be a HeapNumber which is required for freeing the backing // store. ArrayBufferTracker::TearDown(this); tracer_.reset(); isolate()->read_only_heap()->OnHeapTearDown(); read_only_space_ = nullptr; for (int i = FIRST_MUTABLE_SPACE; i <= LAST_MUTABLE_SPACE; i++) { delete space_[i]; space_[i] = nullptr; } memory_allocator()->TearDown(); StrongRootsList* next = nullptr; for (StrongRootsList* list = strong_roots_list_; list; list = next) { next = list->next; delete list; } strong_roots_list_ = nullptr; memory_allocator_.reset(); } void Heap::AddGCPrologueCallback(v8::Isolate::GCCallbackWithData callback, GCType gc_type, void* data) { DCHECK_NOT_NULL(callback); DCHECK(gc_prologue_callbacks_.end() == std::find(gc_prologue_callbacks_.begin(), gc_prologue_callbacks_.end(), GCCallbackTuple(callback, gc_type, data))); gc_prologue_callbacks_.emplace_back(callback, gc_type, data); } void Heap::RemoveGCPrologueCallback(v8::Isolate::GCCallbackWithData callback, void* data) { DCHECK_NOT_NULL(callback); for (size_t i = 0; i < gc_prologue_callbacks_.size(); i++) { if (gc_prologue_callbacks_[i].callback == callback && gc_prologue_callbacks_[i].data == data) { gc_prologue_callbacks_[i] = gc_prologue_callbacks_.back(); gc_prologue_callbacks_.pop_back(); return; } } UNREACHABLE(); } void Heap::AddGCEpilogueCallback(v8::Isolate::GCCallbackWithData callback, GCType gc_type, void* data) { DCHECK_NOT_NULL(callback); DCHECK(gc_epilogue_callbacks_.end() == std::find(gc_epilogue_callbacks_.begin(), gc_epilogue_callbacks_.end(), GCCallbackTuple(callback, gc_type, data))); gc_epilogue_callbacks_.emplace_back(callback, gc_type, data); } void Heap::RemoveGCEpilogueCallback(v8::Isolate::GCCallbackWithData callback, void* data) { DCHECK_NOT_NULL(callback); for (size_t i = 0; i < gc_epilogue_callbacks_.size(); i++) { if (gc_epilogue_callbacks_[i].callback == callback && gc_epilogue_callbacks_[i].data == data) { gc_epilogue_callbacks_[i] = gc_epilogue_callbacks_.back(); gc_epilogue_callbacks_.pop_back(); return; } } UNREACHABLE(); } namespace { Handle<WeakArrayList> CompactWeakArrayList(Heap* heap, Handle<WeakArrayList> array, AllocationType allocation) { if (array->length() == 0) { return array; } int new_length = array->CountLiveWeakReferences(); if (new_length == array->length()) { return array; } Handle<WeakArrayList> new_array = WeakArrayList::EnsureSpace( heap->isolate(), handle(ReadOnlyRoots(heap).empty_weak_array_list(), heap->isolate()), new_length, allocation); // Allocation might have caused GC and turned some of the elements into // cleared weak heap objects. Count the number of live references again and // fill in the new array. int copy_to = 0; for (int i = 0; i < array->length(); i++) { MaybeObject element = array->Get(i); if (element->IsCleared()) continue; new_array->Set(copy_to++, element); } new_array->set_length(copy_to); return new_array; } } // anonymous namespace void Heap::CompactWeakArrayLists(AllocationType allocation) { // Find known PrototypeUsers and compact them. std::vector<Handle<PrototypeInfo>> prototype_infos; { HeapObjectIterator iterator(this); for (HeapObject o = iterator.Next(); !o.is_null(); o = iterator.Next()) { if (o.IsPrototypeInfo()) { PrototypeInfo prototype_info = PrototypeInfo::cast(o); if (prototype_info.prototype_users().IsWeakArrayList()) { prototype_infos.emplace_back(handle(prototype_info, isolate())); } } } } for (auto& prototype_info : prototype_infos) { Handle<WeakArrayList> array( WeakArrayList::cast(prototype_info->prototype_users()), isolate()); DCHECK_IMPLIES(allocation == AllocationType::kOld, InOldSpace(*array) || *array == ReadOnlyRoots(this).empty_weak_array_list()); WeakArrayList new_array = PrototypeUsers::Compact( array, this, JSObject::PrototypeRegistryCompactionCallback, allocation); prototype_info->set_prototype_users(new_array); } // Find known WeakArrayLists and compact them. Handle<WeakArrayList> scripts(script_list(), isolate()); DCHECK_IMPLIES( !V8_ENABLE_THIRD_PARTY_HEAP_BOOL && allocation == AllocationType::kOld, InOldSpace(*scripts)); scripts = CompactWeakArrayList(this, scripts, allocation); set_script_list(*scripts); } void Heap::AddRetainedMap(Handle<NativeContext> context, Handle<Map> map) { if (map->is_in_retained_map_list()) { return; } Handle<WeakArrayList> array(context->retained_maps(), isolate()); if (array->IsFull()) { CompactRetainedMaps(*array); } array = WeakArrayList::AddToEnd(isolate(), array, MaybeObjectHandle::Weak(map)); array = WeakArrayList::AddToEnd( isolate(), array, MaybeObjectHandle(Smi::FromInt(FLAG_retain_maps_for_n_gc), isolate())); if (*array != context->retained_maps()) { context->set_retained_maps(*array); } map->set_is_in_retained_map_list(true); } void Heap::CompactRetainedMaps(WeakArrayList retained_maps) { int length = retained_maps.length(); int new_length = 0; // This loop compacts the array by removing cleared weak cells. for (int i = 0; i < length; i += 2) { MaybeObject maybe_object = retained_maps.Get(i); if (maybe_object->IsCleared()) { continue; } DCHECK(maybe_object->IsWeak()); MaybeObject age = retained_maps.Get(i + 1); DCHECK(age->IsSmi()); if (i != new_length) { retained_maps.Set(new_length, maybe_object); retained_maps.Set(new_length + 1, age); } new_length += 2; } HeapObject undefined = ReadOnlyRoots(this).undefined_value(); for (int i = new_length; i < length; i++) { retained_maps.Set(i, HeapObjectReference::Strong(undefined)); } if (new_length != length) retained_maps.set_length(new_length); } void Heap::FatalProcessOutOfMemory(const char* location) { v8::internal::V8::FatalProcessOutOfMemory(isolate(), location, true); } #ifdef DEBUG class PrintHandleVisitor : public RootVisitor { public: void VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) override { for (FullObjectSlot p = start; p < end; ++p) PrintF(" handle %p to %p\n", p.ToVoidPtr(), reinterpret_cast<void*>((*p).ptr())); } }; void Heap::PrintHandles() { PrintF("Handles:\n"); PrintHandleVisitor v; isolate_->handle_scope_implementer()->Iterate(&v); } #endif class CheckHandleCountVisitor : public RootVisitor { public: CheckHandleCountVisitor() : handle_count_(0) {} ~CheckHandleCountVisitor() override { CHECK_GT(HandleScope::kCheckHandleThreshold, handle_count_); } void VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) override { handle_count_ += end - start; } private: ptrdiff_t handle_count_; }; void Heap::CheckHandleCount() { CheckHandleCountVisitor v; isolate_->handle_scope_implementer()->Iterate(&v); } void Heap::ClearRecordedSlot(HeapObject object, ObjectSlot slot) { #ifndef V8_DISABLE_WRITE_BARRIERS DCHECK(!IsLargeObject(object)); Page* page = Page::FromAddress(slot.address()); if (!page->InYoungGeneration()) { DCHECK_EQ(page->owner_identity(), OLD_SPACE); if (!page->SweepingDone()) { RememberedSet<OLD_TO_NEW>::Remove(page, slot.address()); } } #endif } // static int Heap::InsertIntoRememberedSetFromCode(MemoryChunk* chunk, Address slot) { RememberedSet<OLD_TO_NEW>::Insert<AccessMode::NON_ATOMIC>(chunk, slot); return 0; } #ifdef DEBUG void Heap::VerifyClearedSlot(HeapObject object, ObjectSlot slot) { #ifndef V8_DISABLE_WRITE_BARRIERS DCHECK(!IsLargeObject(object)); if (InYoungGeneration(object)) return; Page* page = Page::FromAddress(slot.address()); DCHECK_EQ(page->owner_identity(), OLD_SPACE); // Slots are filtered with invalidated slots. CHECK_IMPLIES(RememberedSet<OLD_TO_NEW>::Contains(page, slot.address()), page->RegisteredObjectWithInvalidatedSlots<OLD_TO_NEW>(object)); CHECK_IMPLIES(RememberedSet<OLD_TO_OLD>::Contains(page, slot.address()), page->RegisteredObjectWithInvalidatedSlots<OLD_TO_OLD>(object)); #endif } void Heap::VerifySlotRangeHasNoRecordedSlots(Address start, Address end) { #ifndef V8_DISABLE_WRITE_BARRIERS Page* page = Page::FromAddress(start); DCHECK(!page->IsLargePage()); DCHECK(!page->InYoungGeneration()); RememberedSet<OLD_TO_NEW>::CheckNoneInRange(page, start, end); #endif } #endif void Heap::ClearRecordedSlotRange(Address start, Address end) { #ifndef V8_DISABLE_WRITE_BARRIERS Page* page = Page::FromAddress(start); DCHECK(!page->IsLargePage()); if (!page->InYoungGeneration()) { DCHECK_EQ(page->owner_identity(), OLD_SPACE); if (!page->SweepingDone()) { RememberedSet<OLD_TO_NEW>::RemoveRange(page, start, end, SlotSet::KEEP_EMPTY_BUCKETS); } } #endif } PagedSpace* PagedSpaceIterator::Next() { switch (counter_++) { case RO_SPACE: case NEW_SPACE: UNREACHABLE(); case OLD_SPACE: return heap_->old_space(); case CODE_SPACE: return heap_->code_space(); case MAP_SPACE: return heap_->map_space(); default: return nullptr; } } SpaceIterator::SpaceIterator(Heap* heap) : heap_(heap), current_space_(FIRST_MUTABLE_SPACE - 1) {} SpaceIterator::~SpaceIterator() = default; bool SpaceIterator::HasNext() { // Iterate until no more spaces. return current_space_ != LAST_SPACE; } Space* SpaceIterator::Next() { DCHECK(HasNext()); return heap_->space(++current_space_); } class HeapObjectsFilter { public: virtual ~HeapObjectsFilter() = default; virtual bool SkipObject(HeapObject object) = 0; }; class UnreachableObjectsFilter : public HeapObjectsFilter { public: explicit UnreachableObjectsFilter(Heap* heap) : heap_(heap) { MarkReachableObjects(); } ~UnreachableObjectsFilter() override { for (auto it : reachable_) { delete it.second; it.second = nullptr; } } bool SkipObject(HeapObject object) override { if (object.IsFreeSpaceOrFiller()) return true; BasicMemoryChunk* chunk = BasicMemoryChunk::FromHeapObject(object); if (reachable_.count(chunk) == 0) return true; return reachable_[chunk]->count(object) == 0; } private: bool MarkAsReachable(HeapObject object) { BasicMemoryChunk* chunk = BasicMemoryChunk::FromHeapObject(object); if (reachable_.count(chunk) == 0) { reachable_[chunk] = new std::unordered_set<HeapObject, Object::Hasher>(); } if (reachable_[chunk]->count(object)) return false; reachable_[chunk]->insert(object); return true; } class MarkingVisitor : public ObjectVisitor, public RootVisitor { public: explicit MarkingVisitor(UnreachableObjectsFilter* filter) : filter_(filter) {} void VisitPointers(HeapObject host, ObjectSlot start, ObjectSlot end) override { MarkPointers(MaybeObjectSlot(start), MaybeObjectSlot(end)); } void VisitPointers(HeapObject host, MaybeObjectSlot start, MaybeObjectSlot end) final { MarkPointers(start, end); } void VisitCodeTarget(Code host, RelocInfo* rinfo) final { Code target = Code::GetCodeFromTargetAddress(rinfo->target_address()); MarkHeapObject(target); } void VisitEmbeddedPointer(Code host, RelocInfo* rinfo) final { MarkHeapObject(rinfo->target_object()); } void VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) override { MarkPointersImpl(start, end); } void TransitiveClosure() { while (!marking_stack_.empty()) { HeapObject obj = marking_stack_.back(); marking_stack_.pop_back(); obj.Iterate(this); } } private: void MarkPointers(MaybeObjectSlot start, MaybeObjectSlot end) { MarkPointersImpl(start, end); } template <typename TSlot> V8_INLINE void MarkPointersImpl(TSlot start, TSlot end) { // Treat weak references as strong. for (TSlot p = start; p < end; ++p) { typename TSlot::TObject object = *p; HeapObject heap_object; if (object.GetHeapObject(&heap_object)) { MarkHeapObject(heap_object); } } } V8_INLINE void MarkHeapObject(HeapObject heap_object) { if (filter_->MarkAsReachable(heap_object)) { marking_stack_.push_back(heap_object); } } UnreachableObjectsFilter* filter_; std::vector<HeapObject> marking_stack_; }; friend class MarkingVisitor; void MarkReachableObjects() { MarkingVisitor visitor(this); heap_->IterateRoots(&visitor, {}); visitor.TransitiveClosure(); } Heap* heap_; DisallowHeapAllocation no_allocation_; std::unordered_map<BasicMemoryChunk*, std::unordered_set<HeapObject, Object::Hasher>*> reachable_; }; HeapObjectIterator::HeapObjectIterator( Heap* heap, HeapObjectIterator::HeapObjectsFiltering filtering) : heap_(heap), safepoint_scope_(std::make_unique<SafepointScope>(heap)), filtering_(filtering), filter_(nullptr), space_iterator_(nullptr), object_iterator_(nullptr) { heap_->MakeHeapIterable(); // Start the iteration. space_iterator_ = new SpaceIterator(heap_); switch (filtering_) { case kFilterUnreachable: filter_ = new UnreachableObjectsFilter(heap_); break; default: break; } object_iterator_ = space_iterator_->Next()->GetObjectIterator(heap_); } HeapObjectIterator::~HeapObjectIterator() { #ifdef DEBUG // Assert that in filtering mode we have iterated through all // objects. Otherwise, heap will be left in an inconsistent state. if (filtering_ != kNoFiltering) { DCHECK_NULL(object_iterator_); } #endif delete space_iterator_; delete filter_; } HeapObject HeapObjectIterator::Next() { if (filter_ == nullptr) return NextObject(); HeapObject obj = NextObject(); while (!obj.is_null() && (filter_->SkipObject(obj))) obj = NextObject(); return obj; } HeapObject HeapObjectIterator::NextObject() { // No iterator means we are done. if (object_iterator_.get() == nullptr) return HeapObject(); HeapObject obj = object_iterator_.get()->Next(); if (!obj.is_null()) { // If the current iterator has more objects we are fine. return obj; } else { // Go though the spaces looking for one that has objects. while (space_iterator_->HasNext()) { object_iterator_ = space_iterator_->Next()->GetObjectIterator(heap_); obj = object_iterator_.get()->Next(); if (!obj.is_null()) { return obj; } } } // Done with the last space. object_iterator_.reset(nullptr); return HeapObject(); } void Heap::UpdateTotalGCTime(double duration) { if (FLAG_trace_gc_verbose) { total_gc_time_ms_ += duration; } } void Heap::ExternalStringTable::CleanUpYoung() { int last = 0; Isolate* isolate = heap_->isolate(); for (size_t i = 0; i < young_strings_.size(); ++i) { Object o = young_strings_[i]; if (o.IsTheHole(isolate)) { continue; } // The real external string is already in one of these vectors and was or // will be processed. Re-processing it will add a duplicate to the vector. if (o.IsThinString()) continue; DCHECK(o.IsExternalString()); if (InYoungGeneration(o)) { young_strings_[last++] = o; } else { old_strings_.push_back(o); } } young_strings_.resize(last); } void Heap::ExternalStringTable::CleanUpAll() { CleanUpYoung(); int last = 0; Isolate* isolate = heap_->isolate(); for (size_t i = 0; i < old_strings_.size(); ++i) { Object o = old_strings_[i]; if (o.IsTheHole(isolate)) { continue; } // The real external string is already in one of these vectors and was or // will be processed. Re-processing it will add a duplicate to the vector. if (o.IsThinString()) continue; DCHECK(o.IsExternalString()); DCHECK(!InYoungGeneration(o)); old_strings_[last++] = o; } old_strings_.resize(last); #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif } void Heap::ExternalStringTable::TearDown() { for (size_t i = 0; i < young_strings_.size(); ++i) { Object o = young_strings_[i]; // Dont finalize thin strings. if (o.IsThinString()) continue; heap_->FinalizeExternalString(ExternalString::cast(o)); } young_strings_.clear(); for (size_t i = 0; i < old_strings_.size(); ++i) { Object o = old_strings_[i]; // Dont finalize thin strings. if (o.IsThinString()) continue; heap_->FinalizeExternalString(ExternalString::cast(o)); } old_strings_.clear(); } void Heap::RememberUnmappedPage(Address page, bool compacted) { // Tag the page pointer to make it findable in the dump file. if (compacted) { page ^= 0xC1EAD & (Page::kPageSize - 1); // Cleared. } else { page ^= 0x1D1ED & (Page::kPageSize - 1); // I died. } remembered_unmapped_pages_[remembered_unmapped_pages_index_] = page; remembered_unmapped_pages_index_++; remembered_unmapped_pages_index_ %= kRememberedUnmappedPages; } size_t Heap::YoungArrayBufferBytes() { DCHECK(V8_ARRAY_BUFFER_EXTENSION_BOOL); return array_buffer_sweeper()->YoungBytes(); } size_t Heap::OldArrayBufferBytes() { DCHECK(V8_ARRAY_BUFFER_EXTENSION_BOOL); return array_buffer_sweeper()->OldBytes(); } void Heap::RegisterStrongRoots(FullObjectSlot start, FullObjectSlot end) { StrongRootsList* list = new StrongRootsList(); list->next = strong_roots_list_; list->start = start; list->end = end; strong_roots_list_ = list; } void Heap::UnregisterStrongRoots(FullObjectSlot start) { StrongRootsList* prev = nullptr; StrongRootsList* list = strong_roots_list_; while (list != nullptr) { StrongRootsList* next = list->next; if (list->start == start) { if (prev) { prev->next = next; } else { strong_roots_list_ = next; } delete list; } else { prev = list; } list = next; } } void Heap::SetBuiltinsConstantsTable(FixedArray cache) { set_builtins_constants_table(cache); } void Heap::SetDetachedContexts(WeakArrayList detached_contexts) { set_detached_contexts(detached_contexts); } void Heap::SetInterpreterEntryTrampolineForProfiling(Code code) { DCHECK_EQ(Builtins::kInterpreterEntryTrampoline, code.builtin_index()); set_interpreter_entry_trampoline_for_profiling(code); } void Heap::PostFinalizationRegistryCleanupTaskIfNeeded() { // Only one cleanup task is posted at a time. if (!HasDirtyJSFinalizationRegistries() || is_finalization_registry_cleanup_task_posted_) { return; } auto taskrunner = V8::GetCurrentPlatform()->GetForegroundTaskRunner( reinterpret_cast<v8::Isolate*>(isolate())); auto task = std::make_unique<FinalizationRegistryCleanupTask>(this); taskrunner->PostNonNestableTask(std::move(task)); is_finalization_registry_cleanup_task_posted_ = true; } void Heap::EnqueueDirtyJSFinalizationRegistry( JSFinalizationRegistry finalization_registry, std::function<void(HeapObject object, ObjectSlot slot, Object target)> gc_notify_updated_slot) { // Add a FinalizationRegistry to the tail of the dirty list. DCHECK(!HasDirtyJSFinalizationRegistries() || dirty_js_finalization_registries_list().IsJSFinalizationRegistry()); DCHECK(finalization_registry.next_dirty().IsUndefined(isolate())); DCHECK(!finalization_registry.scheduled_for_cleanup()); finalization_registry.set_scheduled_for_cleanup(true); if (dirty_js_finalization_registries_list_tail().IsUndefined(isolate())) { DCHECK(dirty_js_finalization_registries_list().IsUndefined(isolate())); set_dirty_js_finalization_registries_list(finalization_registry); // dirty_js_finalization_registries_list_ is rescanned by // ProcessWeakListRoots. } else { JSFinalizationRegistry tail = JSFinalizationRegistry::cast( dirty_js_finalization_registries_list_tail()); tail.set_next_dirty(finalization_registry); gc_notify_updated_slot( tail, tail.RawField(JSFinalizationRegistry::kNextDirtyOffset), finalization_registry); } set_dirty_js_finalization_registries_list_tail(finalization_registry); // dirty_js_finalization_registries_list_tail_ is rescanned by // ProcessWeakListRoots. } MaybeHandle<JSFinalizationRegistry> Heap::DequeueDirtyJSFinalizationRegistry() { // Take a FinalizationRegistry from the head of the dirty list for fairness. if (HasDirtyJSFinalizationRegistries()) { Handle<JSFinalizationRegistry> head( JSFinalizationRegistry::cast(dirty_js_finalization_registries_list()), isolate()); set_dirty_js_finalization_registries_list(head->next_dirty()); head->set_next_dirty(ReadOnlyRoots(this).undefined_value()); if (*head == dirty_js_finalization_registries_list_tail()) { set_dirty_js_finalization_registries_list_tail( ReadOnlyRoots(this).undefined_value()); } return head; } return {}; } void Heap::RemoveDirtyFinalizationRegistriesOnContext(NativeContext context) { if (!FLAG_harmony_weak_refs) return; DisallowHeapAllocation no_gc; Isolate* isolate = this->isolate(); Object prev = ReadOnlyRoots(isolate).undefined_value(); Object current = dirty_js_finalization_registries_list(); while (!current.IsUndefined(isolate)) { JSFinalizationRegistry finalization_registry = JSFinalizationRegistry::cast(current); if (finalization_registry.native_context() == context) { if (prev.IsUndefined(isolate)) { set_dirty_js_finalization_registries_list( finalization_registry.next_dirty()); } else { JSFinalizationRegistry::cast(prev).set_next_dirty( finalization_registry.next_dirty()); } finalization_registry.set_scheduled_for_cleanup(false); current = finalization_registry.next_dirty(); finalization_registry.set_next_dirty( ReadOnlyRoots(isolate).undefined_value()); } else { prev = current; current = finalization_registry.next_dirty(); } } set_dirty_js_finalization_registries_list_tail(prev); } void Heap::KeepDuringJob(Handle<JSReceiver> target) { DCHECK(FLAG_harmony_weak_refs); DCHECK(weak_refs_keep_during_job().IsUndefined() || weak_refs_keep_during_job().IsOrderedHashSet()); Handle<OrderedHashSet> table; if (weak_refs_keep_during_job().IsUndefined(isolate())) { table = isolate()->factory()->NewOrderedHashSet(); } else { table = handle(OrderedHashSet::cast(weak_refs_keep_during_job()), isolate()); } table = OrderedHashSet::Add(isolate(), table, target).ToHandleChecked(); set_weak_refs_keep_during_job(*table); } void Heap::ClearKeptObjects() { set_weak_refs_keep_during_job(ReadOnlyRoots(isolate()).undefined_value()); } size_t Heap::NumberOfTrackedHeapObjectTypes() { return ObjectStats::OBJECT_STATS_COUNT; } size_t Heap::ObjectCountAtLastGC(size_t index) { if (live_object_stats_ == nullptr || index >= ObjectStats::OBJECT_STATS_COUNT) return 0; return live_object_stats_->object_count_last_gc(index); } size_t Heap::ObjectSizeAtLastGC(size_t index) { if (live_object_stats_ == nullptr || index >= ObjectStats::OBJECT_STATS_COUNT) return 0; return live_object_stats_->object_size_last_gc(index); } bool Heap::GetObjectTypeName(size_t index, const char** object_type, const char** object_sub_type) { if (index >= ObjectStats::OBJECT_STATS_COUNT) return false; switch (static_cast<int>(index)) { #define COMPARE_AND_RETURN_NAME(name) \ case name: \ *object_type = #name; \ *object_sub_type = ""; \ return true; INSTANCE_TYPE_LIST(COMPARE_AND_RETURN_NAME) #undef COMPARE_AND_RETURN_NAME #define COMPARE_AND_RETURN_NAME(name) \ case ObjectStats::FIRST_VIRTUAL_TYPE + ObjectStats::name: \ *object_type = #name; \ *object_sub_type = ""; \ return true; VIRTUAL_INSTANCE_TYPE_LIST(COMPARE_AND_RETURN_NAME) #undef COMPARE_AND_RETURN_NAME } return false; } size_t Heap::NumberOfNativeContexts() { int result = 0; Object context = native_contexts_list(); while (!context.IsUndefined(isolate())) { ++result; Context native_context = Context::cast(context); context = native_context.next_context_link(); } return result; } std::vector<Handle<NativeContext>> Heap::FindAllNativeContexts() { std::vector<Handle<NativeContext>> result; Object context = native_contexts_list(); while (!context.IsUndefined(isolate())) { NativeContext native_context = NativeContext::cast(context); result.push_back(handle(native_context, isolate())); context = native_context.next_context_link(); } return result; } std::vector<WeakArrayList> Heap::FindAllRetainedMaps() { std::vector<WeakArrayList> result; Object context = native_contexts_list(); while (!context.IsUndefined(isolate())) { NativeContext native_context = NativeContext::cast(context); result.push_back(native_context.retained_maps()); context = native_context.next_context_link(); } return result; } size_t Heap::NumberOfDetachedContexts() { // The detached_contexts() array has two entries per detached context. return detached_contexts().length() / 2; } void VerifyPointersVisitor::VisitPointers(HeapObject host, ObjectSlot start, ObjectSlot end) { VerifyPointers(host, MaybeObjectSlot(start), MaybeObjectSlot(end)); } void VerifyPointersVisitor::VisitPointers(HeapObject host, MaybeObjectSlot start, MaybeObjectSlot end) { VerifyPointers(host, start, end); } void VerifyPointersVisitor::VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) { VerifyPointersImpl(start, end); } void VerifyPointersVisitor::VerifyHeapObjectImpl(HeapObject heap_object) { CHECK(IsValidHeapObject(heap_, heap_object)); CHECK(heap_object.map().IsMap()); } template <typename TSlot> void VerifyPointersVisitor::VerifyPointersImpl(TSlot start, TSlot end) { for (TSlot slot = start; slot < end; ++slot) { typename TSlot::TObject object = *slot; HeapObject heap_object; if (object.GetHeapObject(&heap_object)) { VerifyHeapObjectImpl(heap_object); } else { CHECK(object.IsSmi() || object.IsCleared()); } } } void VerifyPointersVisitor::VerifyPointers(HeapObject host, MaybeObjectSlot start, MaybeObjectSlot end) { // If this DCHECK fires then you probably added a pointer field // to one of objects in DATA_ONLY_VISITOR_ID_LIST. You can fix // this by moving that object to POINTER_VISITOR_ID_LIST. DCHECK_EQ(ObjectFields::kMaybePointers, Map::ObjectFieldsFrom(host.map().visitor_id())); VerifyPointersImpl(start, end); } void VerifyPointersVisitor::VisitCodeTarget(Code host, RelocInfo* rinfo) { Code target = Code::GetCodeFromTargetAddress(rinfo->target_address()); VerifyHeapObjectImpl(target); } void VerifyPointersVisitor::VisitEmbeddedPointer(Code host, RelocInfo* rinfo) { VerifyHeapObjectImpl(rinfo->target_object()); } void VerifySmisVisitor::VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) { for (FullObjectSlot current = start; current < end; ++current) { CHECK((*current).IsSmi()); } } bool Heap::AllowedToBeMigrated(Map map, HeapObject obj, AllocationSpace dst) { // Object migration is governed by the following rules: // // 1) Objects in new-space can be migrated to the old space // that matches their target space or they stay in new-space. // 2) Objects in old-space stay in the same space when migrating. // 3) Fillers (two or more words) can migrate due to left-trimming of // fixed arrays in new-space or old space. // 4) Fillers (one word) can never migrate, they are skipped by // incremental marking explicitly to prevent invalid pattern. // // Since this function is used for debugging only, we do not place // asserts here, but check everything explicitly. if (map == ReadOnlyRoots(this).one_pointer_filler_map()) return false; InstanceType type = map.instance_type(); MemoryChunk* chunk = MemoryChunk::FromHeapObject(obj); AllocationSpace src = chunk->owner_identity(); switch (src) { case NEW_SPACE: return dst == NEW_SPACE || dst == OLD_SPACE; case OLD_SPACE: return dst == OLD_SPACE; case CODE_SPACE: return dst == CODE_SPACE && type == CODE_TYPE; case MAP_SPACE: case LO_SPACE: case CODE_LO_SPACE: case NEW_LO_SPACE: case RO_SPACE: return false; } UNREACHABLE(); } size_t Heap::EmbedderAllocationCounter() const { return local_embedder_heap_tracer() ? local_embedder_heap_tracer()->allocated_size() : 0; } void Heap::CreateObjectStats() { if (V8_LIKELY(!TracingFlags::is_gc_stats_enabled())) return; if (!live_object_stats_) { live_object_stats_.reset(new ObjectStats(this)); } if (!dead_object_stats_) { dead_object_stats_.reset(new ObjectStats(this)); } } void AllocationObserver::AllocationStep(int bytes_allocated, Address soon_object, size_t size) { DCHECK_GE(bytes_allocated, 0); bytes_to_next_step_ -= bytes_allocated; if (bytes_to_next_step_ <= 0) { Step(static_cast<int>(step_size_ - bytes_to_next_step_), soon_object, size); step_size_ = GetNextStepSize(); bytes_to_next_step_ = step_size_; } DCHECK_GE(bytes_to_next_step_, 0); } Map Heap::GcSafeMapOfCodeSpaceObject(HeapObject object) { MapWord map_word = object.map_word(); return map_word.IsForwardingAddress() ? map_word.ToForwardingAddress().map() : map_word.ToMap(); } Code Heap::GcSafeCastToCode(HeapObject object, Address inner_pointer) { Code code = Code::unchecked_cast(object); DCHECK(!code.is_null()); DCHECK(GcSafeCodeContains(code, inner_pointer)); return code; } bool Heap::GcSafeCodeContains(Code code, Address addr) { Map map = GcSafeMapOfCodeSpaceObject(code); DCHECK(map == ReadOnlyRoots(this).code_map()); if (InstructionStream::TryLookupCode(isolate(), addr) == code) return true; Address start = code.address(); Address end = code.address() + code.SizeFromMap(map); return start <= addr && addr < end; } Code Heap::GcSafeFindCodeForInnerPointer(Address inner_pointer) { Code code = InstructionStream::TryLookupCode(isolate(), inner_pointer); if (!code.is_null()) return code; if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) { Address start = tp_heap_->GetObjectFromInnerPointer(inner_pointer); return GcSafeCastToCode(HeapObject::FromAddress(start), inner_pointer); } // Check if the inner pointer points into a large object chunk. LargePage* large_page = code_lo_space()->FindPage(inner_pointer); if (large_page != nullptr) { return GcSafeCastToCode(large_page->GetObject(), inner_pointer); } if (V8_LIKELY(code_space()->Contains(inner_pointer))) { // Iterate through the page until we reach the end or find an object // starting after the inner pointer. Page* page = Page::FromAddress(inner_pointer); Address start = page->GetCodeObjectRegistry()->GetCodeObjectStartFromInnerAddress( inner_pointer); return GcSafeCastToCode(HeapObject::FromAddress(start), inner_pointer); } // It can only fall through to here during debugging, where for instance "jco" // was called on an address within a RO_SPACE builtin. It cannot reach here // during stack iteration as RO_SPACE memory is not executable so cannot // appear on the stack as an instruction address. DCHECK(ReadOnlyHeap::Contains( HeapObject::FromAddress(inner_pointer & ~kHeapObjectTagMask))); // TODO(delphick): Possibly optimize this as it iterates over all pages in // RO_SPACE instead of just the one containing the address. ReadOnlyHeapObjectIterator iterator(isolate()->read_only_heap()); for (HeapObject object = iterator.Next(); !object.is_null(); object = iterator.Next()) { if (!object.IsCode()) continue; Code code = Code::cast(object); if (inner_pointer >= code.address() && inner_pointer < code.address() + code.Size()) { return code; } } UNREACHABLE(); } void Heap::WriteBarrierForCodeSlow(Code code) { for (RelocIterator it(code, RelocInfo::EmbeddedObjectModeMask()); !it.done(); it.next()) { GenerationalBarrierForCode(code, it.rinfo(), it.rinfo()->target_object()); MarkingBarrierForCode(code, it.rinfo(), it.rinfo()->target_object()); } } void Heap::MarkingBarrierForArrayBufferExtensionSlow( HeapObject object, ArrayBufferExtension* extension) { if (V8_CONCURRENT_MARKING_BOOL || GetIsolateFromWritableObject(object) ->heap() ->incremental_marking() ->marking_state() ->IsBlack(object)) extension->Mark(); } void Heap::GenerationalBarrierSlow(HeapObject object, Address slot, HeapObject value) { MemoryChunk* chunk = MemoryChunk::FromHeapObject(object); RememberedSet<OLD_TO_NEW>::Insert<AccessMode::NON_ATOMIC>(chunk, slot); } void Heap::RecordEphemeronKeyWrite(EphemeronHashTable table, Address slot) { DCHECK(ObjectInYoungGeneration(HeapObjectSlot(slot).ToHeapObject())); int slot_index = EphemeronHashTable::SlotToIndex(table.address(), slot); InternalIndex entry = EphemeronHashTable::IndexToEntry(slot_index); auto it = ephemeron_remembered_set_.insert({table, std::unordered_set<int>()}); it.first->second.insert(entry.as_int()); } void Heap::EphemeronKeyWriteBarrierFromCode(Address raw_object, Address key_slot_address, Isolate* isolate) { EphemeronHashTable table = EphemeronHashTable::cast(Object(raw_object)); MaybeObjectSlot key_slot(key_slot_address); MaybeObject maybe_key = *key_slot; HeapObject key; if (!maybe_key.GetHeapObject(&key)) return; if (!ObjectInYoungGeneration(table) && ObjectInYoungGeneration(key)) { isolate->heap()->RecordEphemeronKeyWrite(table, key_slot_address); } isolate->heap()->incremental_marking()->RecordWrite(table, key_slot, maybe_key); } enum RangeWriteBarrierMode { kDoGenerational = 1 << 0, kDoMarking = 1 << 1, kDoEvacuationSlotRecording = 1 << 2, }; template <int kModeMask, typename TSlot> void Heap::WriteBarrierForRangeImpl(MemoryChunk* source_page, HeapObject object, TSlot start_slot, TSlot end_slot) { // At least one of generational or marking write barrier should be requested. STATIC_ASSERT(kModeMask & (kDoGenerational | kDoMarking)); // kDoEvacuationSlotRecording implies kDoMarking. STATIC_ASSERT(!(kModeMask & kDoEvacuationSlotRecording) || (kModeMask & kDoMarking)); IncrementalMarking* incremental_marking = this->incremental_marking(); MarkCompactCollector* collector = this->mark_compact_collector(); for (TSlot slot = start_slot; slot < end_slot; ++slot) { typename TSlot::TObject value = *slot; HeapObject value_heap_object; if (!value.GetHeapObject(&value_heap_object)) continue; if ((kModeMask & kDoGenerational) && Heap::InYoungGeneration(value_heap_object)) { RememberedSet<OLD_TO_NEW>::Insert<AccessMode::NON_ATOMIC>(source_page, slot.address()); } if ((kModeMask & kDoMarking) && incremental_marking->BaseRecordWrite(object, value_heap_object)) { if (kModeMask & kDoEvacuationSlotRecording) { collector->RecordSlot(source_page, HeapObjectSlot(slot), value_heap_object); } } } } // Instantiate Heap::WriteBarrierForRange() for ObjectSlot and MaybeObjectSlot. template void Heap::WriteBarrierForRange<ObjectSlot>(HeapObject object, ObjectSlot start_slot, ObjectSlot end_slot); template void Heap::WriteBarrierForRange<MaybeObjectSlot>( HeapObject object, MaybeObjectSlot start_slot, MaybeObjectSlot end_slot); template <typename TSlot> void Heap::WriteBarrierForRange(HeapObject object, TSlot start_slot, TSlot end_slot) { MemoryChunk* source_page = MemoryChunk::FromHeapObject(object); base::Flags<RangeWriteBarrierMode> mode; if (!source_page->InYoungGeneration()) { mode |= kDoGenerational; } if (incremental_marking()->IsMarking()) { mode |= kDoMarking; if (!source_page->ShouldSkipEvacuationSlotRecording<AccessMode::ATOMIC>()) { mode |= kDoEvacuationSlotRecording; } } switch (mode) { // Nothing to be done. case 0: return; // Generational only. case kDoGenerational: return WriteBarrierForRangeImpl<kDoGenerational>(source_page, object, start_slot, end_slot); // Marking, no evacuation slot recording. case kDoMarking: return WriteBarrierForRangeImpl<kDoMarking>(source_page, object, start_slot, end_slot); // Marking with evacuation slot recording. case kDoMarking | kDoEvacuationSlotRecording: return WriteBarrierForRangeImpl<kDoMarking | kDoEvacuationSlotRecording>( source_page, object, start_slot, end_slot); // Generational and marking, no evacuation slot recording. case kDoGenerational | kDoMarking: return WriteBarrierForRangeImpl<kDoGenerational | kDoMarking>( source_page, object, start_slot, end_slot); // Generational and marking with evacuation slot recording. case kDoGenerational | kDoMarking | kDoEvacuationSlotRecording: return WriteBarrierForRangeImpl<kDoGenerational | kDoMarking | kDoEvacuationSlotRecording>( source_page, object, start_slot, end_slot); default: UNREACHABLE(); } } void Heap::GenerationalBarrierForCodeSlow(Code host, RelocInfo* rinfo, HeapObject object) { DCHECK(InYoungGeneration(object)); Page* source_page = Page::FromHeapObject(host); RelocInfo::Mode rmode = rinfo->rmode(); Address addr = rinfo->pc(); SlotType slot_type = SlotTypeForRelocInfoMode(rmode); if (rinfo->IsInConstantPool()) { addr = rinfo->constant_pool_entry_address(); if (RelocInfo::IsCodeTargetMode(rmode)) { slot_type = CODE_ENTRY_SLOT; } else if (RelocInfo::IsCompressedEmbeddedObject(rmode)) { slot_type = COMPRESSED_OBJECT_SLOT; } else { DCHECK(RelocInfo::IsFullEmbeddedObject(rmode)); slot_type = FULL_OBJECT_SLOT; } } uintptr_t offset = addr - source_page->address(); DCHECK_LT(offset, static_cast<uintptr_t>(TypedSlotSet::kMaxOffset)); RememberedSet<OLD_TO_NEW>::InsertTyped(source_page, slot_type, static_cast<uint32_t>(offset)); } void Heap::MarkingBarrierSlow(HeapObject object, Address slot, HeapObject value) { Heap* heap = Heap::FromWritableHeapObject(object); heap->incremental_marking()->RecordWriteSlow(object, HeapObjectSlot(slot), value); } void Heap::MarkingBarrierForCodeSlow(Code host, RelocInfo* rinfo, HeapObject object) { Heap* heap = Heap::FromWritableHeapObject(host); DCHECK(heap->incremental_marking()->IsMarking()); heap->incremental_marking()->RecordWriteIntoCode(host, rinfo, object); } void Heap::MarkingBarrierForDescriptorArraySlow(Heap* heap, HeapObject host, HeapObject raw_descriptor_array, int number_of_own_descriptors) { DCHECK(heap->incremental_marking()->IsMarking()); DescriptorArray descriptor_array = DescriptorArray::cast(raw_descriptor_array); int16_t raw_marked = descriptor_array.raw_number_of_marked_descriptors(); if (NumberOfMarkedDescriptors::decode(heap->mark_compact_collector()->epoch(), raw_marked) < number_of_own_descriptors) { heap->mark_compact_collector()->MarkDescriptorArrayFromWriteBarrier( host, descriptor_array, number_of_own_descriptors); } } bool Heap::PageFlagsAreConsistent(HeapObject object) { if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) { return true; } BasicMemoryChunk* chunk = BasicMemoryChunk::FromHeapObject(object); heap_internals::MemoryChunk* slim_chunk = heap_internals::MemoryChunk::FromHeapObject(object); // Slim chunk flags consistency. CHECK_EQ(chunk->InYoungGeneration(), slim_chunk->InYoungGeneration()); CHECK_EQ(chunk->IsFlagSet(MemoryChunk::INCREMENTAL_MARKING), slim_chunk->IsMarking()); AllocationSpace identity = chunk->owner()->identity(); // Generation consistency. CHECK_EQ(identity == NEW_SPACE || identity == NEW_LO_SPACE, slim_chunk->InYoungGeneration()); // Read-only consistency. CHECK_EQ(chunk->InReadOnlySpace(), slim_chunk->InReadOnlySpace()); // Marking consistency. if (chunk->IsWritable() && !Heap::InOffThreadSpace(object)) { // RO_SPACE can be shared between heaps, so we can't use RO_SPACE objects to // find a heap. The exception is when the ReadOnlySpace is writeable, during // bootstrapping, so explicitly allow this case. Heap* heap = Heap::FromWritableHeapObject(object); CHECK_EQ(slim_chunk->IsMarking(), heap->incremental_marking()->IsMarking()); } else { // Non-writable RO_SPACE must never have marking flag set. CHECK(!slim_chunk->IsMarking()); } return true; } void Heap::SetEmbedderStackStateForNextFinalizaton( EmbedderHeapTracer::EmbedderStackState stack_state) { local_embedder_heap_tracer()->SetEmbedderStackStateForNextFinalization( stack_state); } #ifdef DEBUG void Heap::IncrementObjectCounters() { isolate_->counters()->objs_since_last_full()->Increment(); isolate_->counters()->objs_since_last_young()->Increment(); } #endif // DEBUG } // namespace internal } // namespace v8