Oilpan: We shouldn't trigger too many conservative GCs when detaching iframes

third_party/WebKit/Source/platform/heap/ThreadState.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 81 matching lines @@
     , m_startOfStack(reinterpret_cast<intptr_t*>(StackFrameDepth::getStackStart()))
     , m_endOfStack(reinterpret_cast<intptr_t*>(StackFrameDepth::getStackStart()))
     , m_safePointScopeMarker(nullptr)
     , m_atSafePoint(false)
     , m_interruptors()
     , m_sweepForbidden(false)
     , m_noAllocationCount(0)
     , m_gcForbiddenCount(0)
     , m_persistentAllocated(0)
     , m_persistentFreed(0)
+    , m_disposedV8ContextCount(0)
     , m_vectorBackingHeapIndex(Vector1HeapIndex)
     , m_currentHeapAges(0)
     , m_isTerminating(false)
     , m_gcMixinMarker(nullptr)
     , m_shouldFlushHeapDoesNotContainCache(false)
     , m_gcState(NoGCScheduled)
     , m_traceDOMWrappers(nullptr)
 #if defined(ADDRESS_SANITIZER)
     , m_asanFakeStack(__asan_get_current_fake_stack())
 #endif
@@ skipping 612 matching lines @@
         schedulePageNavigationGC();
 }
 
 void ThreadState::schedulePageNavigationGC()
 {
     ASSERT(checkThread());
     ASSERT(!isSweepingInProgress());
     setGCState(PageNavigationGCScheduled);
 }
 
+void ThreadState::v8ContextCreated()
+{
+    if (m_disposedV8ContextCount >= 5) {
+        // A frame retains a lot of memory in the V8 side. V8's GC cannot
+        // collect the memory until Oilpan's GC collects the frame. So we
+        // force a conservative GC if no Oilpan's GC has been observed in
+        // the past 5 frame navigations.
+        //
+        // We force a conservative GC not in v8ContextDisposed but in
+        // v8ContextCreated. This avoids triggering too many conservative
+        // GCs when a frame that has a lot of iframes gets detached.
+        Heap::collectGarbage(HeapPointersOnStack, GCWithoutSweep, Heap::ConservativeGC);
+        return;
+    }
+}
+
+void ThreadState::v8ContextDisposed()
+{
+    ++m_disposedV8ContextCount;
+}
+
 void ThreadState::scheduleGCIfNeeded()
 {
     ASSERT(checkThread());
     Heap::reportMemoryUsageForTracing();
 
     if (isGCForbidden())
         return;
 
     // Allocation is allowed during sweeping, but those allocations should not
     // trigger nested GCs.
@@ skipping 252 matching lines @@
 }
 
 void ThreadState::preGC()
 {
     ASSERT(!isInGC());
     setGCState(GCRunning);
     makeConsistentForGC();
     flushHeapDoesNotContainCacheIfNeeded();
     clearHeapAges();
     updatePersistentCounters();
+    m_disposedV8ContextCount = 0;
 }
 
 void ThreadState::postGC(GCType gcType)
 {
     ASSERT(isInGC());
 
 #if ENABLE(GC_PROFILING)
     // We snapshot the heap prior to sweeping to get numbers for both resources
     // that have been allocated since the last GC and for resources that are
     // going to be freed.
@@ skipping 606 matching lines @@
         json->beginArray(it->key.ascii().data());
         for (size_t age = 0; age <= maxHeapObjectAge; ++age)
             json->pushInteger(it->value.ages[age]);
         json->endArray();
     }
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
 }
 #endif
 
 } // namespace blink