heap: Stop sweeper tasks during Isolate::Deinit

Avoid stray sweeper tasks still accessing heap after teardown has been
initiated. This reverts https://crrev.com/c/2297466 and restores the
invariant that no GC is running during teardown.

Bug: v8:12025
Change-Id: I9974a63ef385783a9c3ec09725dce118f754b25f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3081615Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76219}

src/execution/isolate.cc

@@ -3138,12 +3138,6 @@ void Isolate::Deinit() {
   // All client isolates should already be detached.
   DCHECK_NULL(client_isolate_head_);
 
-  // Help sweeper threads complete sweeping to stop faster.
-  heap_.mark_compact_collector()->DrainSweepingWorklists();
-  heap_.mark_compact_collector()->sweeper()->EnsureIterabilityCompleted();
-
-  heap_.memory_allocator()->unmapper()->EnsureUnmappingCompleted();
-
   DumpAndResetStats();
 
   if (FLAG_print_deopt_stress) {

src/heap/heap.cc

@@ -5866,6 +5866,12 @@ void Heap::RegisterExternallyReferencedObject(Address* location) {
 }
 
 void Heap::StartTearDown() {
+  // Finish any ongoing sweeping to avoid stray background tasks still accessing
+  // the heap during teardown.
+  CompleteSweepingFull();
+
+  memory_allocator()->unmapper()->EnsureUnmappingCompleted();
+
   SetGCState(TEAR_DOWN);
 
   // Background threads may allocate and block until GC is performed. However

src/heap/mark-compact.cc

@@ -666,11 +666,6 @@ void MarkCompactCollector::EnsurePageIsSwept(Page* page) {
   sweeper()->EnsurePageIsSwept(page);
 }
 
-void MarkCompactCollector::DrainSweepingWorklists() {
-  if (!sweeper()->sweeping_in_progress()) return;
-  sweeper()->DrainSweepingWorklists();
-}
-
 void MarkCompactCollector::DrainSweepingWorklistForSpace(
     AllocationSpace space) {
   if (!sweeper()->sweeping_in_progress()) return;

src/heap/mark-compact.h

@@ -515,7 +515,6 @@ class MarkCompactCollector final : public MarkCompactCollectorBase {
 
   void EnsurePageIsSwept(Page* page);
 
-  void DrainSweepingWorklists();
   void DrainSweepingWorklistForSpace(AllocationSpace space);
 
   // Checks if sweeping is in progress right now on any space.

src/heap/sweeper.cc

@@ -227,13 +227,6 @@ void Sweeper::EnsureCompleted() {
   sweeping_in_progress_ = false;
 }
 
-void Sweeper::DrainSweepingWorklists() {
-  if (!sweeping_in_progress_) return;
-
-  ForAllSweepingSpaces(
-      [this](AllocationSpace space) { DrainSweepingWorklistForSpace(space); });
-}
-
 void Sweeper::DrainSweepingWorklistForSpace(AllocationSpace space) {
   if (!sweeping_in_progress_) return;
   ParallelSweepSpace(space, 0);

src/heap/sweeper.h

@@ -111,7 +111,6 @@ class Sweeper {
   void StartSweeping();
   V8_EXPORT_PRIVATE void StartSweeperTasks();
   void EnsureCompleted();
-  void DrainSweepingWorklists();
   void DrainSweepingWorklistForSpace(AllocationSpace space);
   bool AreSweeperTasksRunning();