heap: Remove page navigation GC

Garbage collections on page navigations are also initiated by V8 (see
v8::Heap::NotifyContextDisposed for non-dependent contexts) using its
memory reducer mechanism. Since they cover Blink with with unified heap
we do not need to schedule anything else there.

Bug: 948807
Change-Id: I17a7d9235fd80b8cfc91fd55cab904873166056f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1605408Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658988}

third_party/blink/renderer/core/loader/frame_loader.cc

@@ -936,18 +936,6 @@ bool FrameLoader::PrepareForCommit() {
   PluginScriptForbiddenScope forbid_plugin_destructor_scripting;
   DocumentLoader* pdl = provisional_document_loader_;
 
-  if (frame_->GetDocument()) {
-    unsigned node_count = 0;
-    for (Frame* frame = frame_; frame; frame = frame->Tree().TraverseNext()) {
-      if (auto* local_frame = DynamicTo<LocalFrame>(frame))
-        node_count += local_frame->GetDocument()->NodeCount();
-    }
-    unsigned total_node_count =
-        InstanceCounters::CounterValue(InstanceCounters::kNodeCounter);
-    float ratio = static_cast<float>(node_count) / total_node_count;
-    ThreadState::Current()->SchedulePageNavigationGCIfNeeded(ratio);
-  }
-
   // Don't allow this frame to navigate anymore. This line is needed for
   // navigation triggered from children's unload handlers. Blocking navigations
   // triggered from this frame's unload handler is already covered in

third_party/blink/renderer/platform/heap/blink_gc.cc

@@ -18,8 +18,6 @@ const char* BlinkGC::ToString(BlinkGC::GCReason reason) {
       return "ForcedGCForTesting";
     case BlinkGC::GCReason::kMemoryPressureGC:
       return "MemoryPressureGC";
-    case BlinkGC::GCReason::kPageNavigationGC:
-      return "PageNavigationGC";
     case BlinkGC::GCReason::kThreadTerminationGC:
       return "ThreadTerminationGC";
     case BlinkGC::GCReason::kIncrementalV8FollowupGC:

third_party/blink/renderer/platform/heap/blink_gc.h

@@ -94,7 +94,7 @@ class PLATFORM_EXPORT BlinkGC final {
     kConservativeGC = 2,
     kForcedGCForTesting = 3,
     kMemoryPressureGC = 4,
-    kPageNavigationGC = 5,
+    // kPageNavigationGC = 5,
     kThreadTerminationGC = 6,
     // kTesting = 7,
     // kIncrementalIdleGC = 8,

third_party/blink/renderer/platform/heap/thread_state.cc

@@ -415,16 +415,6 @@ bool ThreadState::ShouldScheduleV8FollowupGC() {
                           32 * 1024 * 1024, 1.5);
 }
 
-bool ThreadState::ShouldSchedulePageNavigationGC(
-    float estimated_removal_ratio) {
-  // If estimatedRemovalRatio is low we should let IdleGC handle this.
-  if (estimated_removal_ratio < 0.01)
-    return false;
-  return JudgeGCThreshold(kDefaultAllocatedObjectSizeThreshold,
-                          32 * 1024 * 1024,
-                          1.5 * (1 - estimated_removal_ratio));
-}
-
 bool ThreadState::ShouldForceConservativeGC() {
   // TODO(haraken): 400% is too large. Lower the heap growing factor.
   return JudgeGCThreshold(kDefaultAllocatedObjectSizeThreshold,
@@ -487,44 +477,6 @@ void ThreadState::WillStartV8GC(BlinkGC::V8GCType gc_type) {
     CompleteSweep();
 }
 
-void ThreadState::SchedulePageNavigationGCIfNeeded(
-    float estimated_removal_ratio) {
-  VLOG(2) << "[state:" << this << "] SchedulePageNavigationGCIfNeeded: "
-          << "estimatedRemovalRatio=" << std::setprecision(2)
-          << estimated_removal_ratio;
-  DCHECK(CheckThread());
-
-  if (IsGCForbidden())
-    return;
-
-  // Finish on-going lazy sweeping.
-  // TODO(haraken): It might not make sense to force completeSweep() for all
-  // page navigations.
-  CompleteSweep();
-  DCHECK(!IsSweepingInProgress());
-  DCHECK(!SweepForbidden());
-
-  if (ShouldForceMemoryPressureGC()) {
-    VLOG(2) << "[state:" << this << "] "
-            << "SchedulePageNavigationGCIfNeeded: Scheduled memory pressure GC";
-    CollectGarbage(BlinkGC::kHeapPointersOnStack, BlinkGC::kAtomicMarking,
-                   BlinkGC::kLazySweeping,
-                   BlinkGC::GCReason::kMemoryPressureGC);
-    return;
-  }
-  if (ShouldSchedulePageNavigationGC(estimated_removal_ratio)) {
-    VLOG(2) << "[state:" << this << "] "
-            << "SchedulePageNavigationGCIfNeeded: Scheduled page navigation GC";
-    SchedulePageNavigationGC();
-  }
-}
-
-void ThreadState::SchedulePageNavigationGC() {
-  DCHECK(CheckThread());
-  DCHECK(!IsSweepingInProgress());
-  SetGCState(kPageNavigationGCScheduled);
-}
-
 void ThreadState::ScheduleForcedGCForTesting() {
   DCHECK(CheckThread());
   CompleteSweep();
@@ -677,7 +629,6 @@ void UnexpectedGCState(ThreadState::GCState gc_state) {
     UNEXPECTED_GCSTATE(kIncrementalMarkingStepPaused);
     UNEXPECTED_GCSTATE(kIncrementalMarkingStepScheduled);
     UNEXPECTED_GCSTATE(kIncrementalMarkingFinalizeScheduled);
-    UNEXPECTED_GCSTATE(kPageNavigationGCScheduled);
     UNEXPECTED_GCSTATE(kIncrementalGCScheduled);
   }
 }
@@ -697,7 +648,6 @@ void ThreadState::SetGCState(GCState gc_state) {
       VERIFY_STATE_TRANSITION(
           gc_state_ == kNoGCScheduled || gc_state_ == kPreciseGCScheduled ||
           gc_state_ == kForcedGCForTestingScheduled ||
-          gc_state_ == kPageNavigationGCScheduled ||
           gc_state_ == kIncrementalMarkingStepPaused ||
           gc_state_ == kIncrementalMarkingStepScheduled ||
           gc_state_ == kIncrementalMarkingFinalizeScheduled ||
@@ -714,7 +664,6 @@ void ThreadState::SetGCState(GCState gc_state) {
       VERIFY_STATE_TRANSITION(gc_state_ == kIncrementalMarkingStepScheduled);
       break;
     case kForcedGCForTestingScheduled:
-    case kPageNavigationGCScheduled:
     case kPreciseGCScheduled:
       DCHECK(CheckThread());
       DCHECK(!IsSweepingInProgress());
@@ -725,7 +674,6 @@ void ThreadState::SetGCState(GCState gc_state) {
                                   kIncrementalMarkingFinalizeScheduled ||
                               gc_state_ == kPreciseGCScheduled ||
                               gc_state_ == kForcedGCForTestingScheduled ||
-                              gc_state_ == kPageNavigationGCScheduled ||
                               gc_state_ == kIncrementalGCScheduled);
       break;
     case kIncrementalGCScheduled:
@@ -786,11 +734,6 @@ void ThreadState::RunScheduledGC(BlinkGC::StackState stack_state) {
       CollectGarbage(BlinkGC::kNoHeapPointersOnStack, BlinkGC::kAtomicMarking,
                      BlinkGC::kLazySweeping, BlinkGC::GCReason::kPreciseGC);
       break;
-    case kPageNavigationGCScheduled:
-      CollectGarbage(BlinkGC::kNoHeapPointersOnStack, BlinkGC::kAtomicMarking,
-                     BlinkGC::kEagerSweeping,
-                     BlinkGC::GCReason::kPageNavigationGC);
-      break;
     case kIncrementalMarkingStepScheduled:
       IncrementalMarkingStep(stack_state);
       break;
@@ -1121,7 +1064,6 @@ void UpdateHistograms(const ThreadHeapStatsCollector::Event& event) {
     COUNT_BY_GC_REASON(ConservativeGC)
     COUNT_BY_GC_REASON(ForcedGCForTesting)
     COUNT_BY_GC_REASON(MemoryPressureGC)
-    COUNT_BY_GC_REASON(PageNavigationGC)
     COUNT_BY_GC_REASON(ThreadTerminationGC)
     COUNT_BY_GC_REASON(IncrementalV8FollowupGC)
     COUNT_BY_GC_REASON(UnifiedHeapGC)
@@ -1460,7 +1402,6 @@ void ThreadState::CollectGarbage(BlinkGC::StackState stack_state,
     COUNT_BY_GC_REASON(ConservativeGC)
     COUNT_BY_GC_REASON(ForcedGCForTesting)
     COUNT_BY_GC_REASON(MemoryPressureGC)
-    COUNT_BY_GC_REASON(PageNavigationGC)
     COUNT_BY_GC_REASON(ThreadTerminationGC)
     COUNT_BY_GC_REASON(IncrementalV8FollowupGC)
     COUNT_BY_GC_REASON(UnifiedHeapGC)

third_party/blink/renderer/platform/heap/thread_state.h

@@ -151,7 +151,6 @@ class PLATFORM_EXPORT ThreadState final : private RAILModeObserver {
     kIncrementalMarkingFinalizeScheduled,
     kPreciseGCScheduled,
     kForcedGCForTestingScheduled,
-    kPageNavigationGCScheduled,
     kIncrementalGCScheduled,
   };
 
@@ -224,8 +223,6 @@ class PLATFORM_EXPORT ThreadState final : private RAILModeObserver {
   void SchedulePreciseGC();
   void ScheduleIncrementalGC(BlinkGC::GCReason);
   void ScheduleV8FollowupGCIfNeeded(BlinkGC::V8GCType);
-  void SchedulePageNavigationGCIfNeeded(float estimated_removal_ratio);
-  void SchedulePageNavigationGC();
   void ScheduleForcedGCForTesting();
   void ScheduleGCIfNeeded();
   void PostIdleGCTask();
@@ -491,11 +488,6 @@ class PLATFORM_EXPORT ThreadState final : private RAILModeObserver {
   // V8 minor or major GC is likely to drop a lot of references to objects
   // on Oilpan's heap. We give a chance to schedule a GC.
   bool ShouldScheduleV8FollowupGC();
-  // Page navigation is likely to drop a lot of references to objects
-  // on Oilpan's heap. We give a chance to schedule a GC.
-  // estimatedRemovalRatio is the estimated ratio of objects that will be no
-  // longer necessary due to the navigation.
-  bool ShouldSchedulePageNavigationGC(float estimated_removal_ratio);
 
   // Internal helpers to handle memory pressure conditions.