Tune the memory pressure handler to perform a second GC immediately

after the first GC if time allows and there is memory to be freed.

BUG=chromium:618958
LOG=NO

Review-Url: https://codereview.chromium.org/2057103002
Cr-Commit-Position: refs/heads/master@{#36894}

src/heap/heap.cc

@@ -4466,8 +4466,36 @@ void Heap::CheckMemoryPressure() {
 }
 
 void Heap::CollectGarbageOnMemoryPressure(const char* source) {
+  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 | kAbortIncrementalMarkingMask,
-                    source);
+                    source, kGCCallbackFlagCollectAllAvailableGarbage);
+  double end = MonotonicallyIncreasingTimeInMs();
+
+  // Estimate how much memory we can free.
+  int64_t potential_garbage = (CommittedMemory() - SizeOfObjects()) +
+                              amount_of_external_allocated_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 | kAbortIncrementalMarkingMask, source,
+          kGCCallbackFlagCollectAllAvailableGarbage);
+    } else {
+      if (FLAG_incremental_marking && incremental_marking()->IsStopped()) {
+        StartIdleIncrementalMarking();
+      }
+    }
+  }
 }
 
 void Heap::MemoryPressureNotification(MemoryPressureLevel level,

test/cctest/heap/test-heap.cc

@@ -6761,5 +6761,23 @@ TEST(Regress615489) {
   CHECK_LE(size_after, size_before);
 }
 
+TEST(Regress618958) {
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  Heap* heap = CcTest::heap();
+  bool isolate_is_locked = true;
+  heap->update_amount_of_external_allocated_memory(100 * MB);
+  int mark_sweep_count_before = heap->ms_count();
+  heap->MemoryPressureNotification(MemoryPressureLevel::kCritical,
+                                   isolate_is_locked);
+  int mark_sweep_count_after = heap->ms_count();
+  int mark_sweeps_performed = mark_sweep_count_after - mark_sweep_count_before;
+  // The memory pressuer handler either performed two GCs or performed one and
+  // started incremental marking.
+  CHECK(mark_sweeps_performed == 2 ||
+        (mark_sweeps_performed == 1 &&
+         !heap->incremental_marking()->IsStopped()));
+}
+
 }  // namespace internal
 }  // namespace v8