Oilpan: Schedule a conservative GC when page navigations are happening frequently

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index 8d2eb9f6f6f2495de33ea25adf3dc679516bd960..6b568dfb3b601bae49df714fac2a4c762cc6dbf9 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -99,6 +99,7 @@ ThreadState::ThreadState()
     , m_gcForbiddenCount(0)
     , m_persistentAllocated(0)
     , m_persistentFreed(0)
+    , m_pageNavigationCount(0)
     , m_vectorBackingHeapIndex(Vector1HeapIndex)
     , m_currentHeapAges(0)
     , m_isTerminating(false)
@@ -703,6 +704,16 @@ void ThreadState::schedulePageNavigationGCIfNeeded(float estimatedRemovalRatio)
     ASSERT(!isSweepingInProgress());
     ASSERT(!sweepForbidden());
 
+    ++m_pageNavigationCount;
+    if (m_pageNavigationCount >= 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.
+        Heap::collectGarbage(HeapPointersOnStack, GCWithoutSweep, Heap::ConservativeGC);
+        return;
+    }
+
     if (shouldSchedulePageNavigationGC(estimatedRemovalRatio))
         schedulePageNavigationGC();
 }
@@ -1397,6 +1408,7 @@ void ThreadState::clearHeapAges()
     memset(m_heapAges, 0, sizeof(size_t) * NumberOfHeaps);
     memset(m_likelyToBePromptlyFreed.get(), 0, sizeof(int) * likelyToBePromptlyFreedArraySize);
     m_currentHeapAges = 0;
+    m_pageNavigationCount = 0;

[keishi, 2015/09/19 06:12:15]

nit: I'm not sure if this belongs here because it isn't related to heapAges.

[haraken, 2015/09/19 08:17:14]

Moved this to preGC.

 }
 
 int ThreadState::heapIndexOfVectorHeapLeastRecentlyExpanded(int beginHeapIndex, int endHeapIndex)