Allow Oilpan heap objects account for their external allocations.

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 651 matching lines @@
     // but not for less than 512 KB.
     size_t newSize = Heap::allocatedObjectSize();
     return newSize >= 512 * 1024 && newSize > Heap::markedObjectSize() / 2;
 #endif
 }
 
 // FIXME: We should improve the GC heuristics.
 // These heuristics affect performance significantly.
 bool ThreadState::shouldForceConservativeGC()
 {
+    if (Heap::isGCUrgentlyRequested())
+        return true;
+
     size_t newSize = Heap::allocatedObjectSize();
     if (newSize >= 300 * 1024 * 1024) {
         // If we consume too much memory, trigger a conservative GC
         // on a 50% increase in size since the last GC. This is a safe guard
         // to avoid OOM.
         return newSize > Heap::markedObjectSize() / 2;
     }
     if (m_didV8GCAfterLastGC && m_collectionRate > 0.5) {
         // If we had a V8 GC after the last Oilpan GC and the last collection
         // rate was higher than 50%, trigger a conservative GC on a 200%
         // increase in size since the last GC, but not for less than 4 MB.
         return newSize >= 4 * 1024 * 1024 && newSize > 2 * Heap::markedObjectSize();
     }
     // Otherwise, trigger a conservative GC on a 400% increase in size since
     // the last GC, but not for less than 32 MB. We set the higher limit in
     // this case because Oilpan GC is unlikely to collect a lot of objects
     // without having a V8 GC.
     return newSize >= 32 * 1024 * 1024 && newSize > 4 * Heap::markedObjectSize();
 }
 
 void ThreadState::scheduleGCIfNeeded()
 {
     checkThread();
     // Allocation is allowed during sweeping, but those allocations should not
     // trigger nested GCs
-    if (isSweepingInProgress())
-        return;
+    if (isSweepingInProgress()) {
+        if (!Heap::isGCUrgentlyRequested() || !isSweepingScheduled())

[haraken, 2015/02/19 23:47:44]

As commented earlier, I guess we should just call completeSweep() if an urgent
GC is scheduled.

Note that scheduleGCIfNeeded can be called by outOfLineAllocate, where it's not
guaranteed that sweeping is complete.

So I still think that something like:
is what we want.

[sof, 2015/02/20 09:33:49]

This will already happen when the collectGarbage() for the conservative GC goes
ahead just below, as previously explained.

[haraken, 2015/02/23 08:42:27]

Makes sense.

+            return;
+        // Urgent GC requested with only a GC scheduled; fall through
+        // and have it be serviced by a conservative GC.
+    }
     ASSERT(!sweepForbidden());
 
-    if (shouldForceConservativeGC())
-        Heap::collectGarbage(ThreadState::HeapPointersOnStack, ThreadState::GCWithoutSweep);
-    else if (shouldSchedulePreciseGC())
+    if (shouldForceConservativeGC()) {

[haraken, 2015/02/19 23:47:44]

Slightly better:

if (Heap::isGCUrgentlyRequested()) {
  completeSweep();
  Heap::clearUrgentGC();
  Heap::collectGarbage(HeapPointersOnStack, GCWithSweep);
  return;
}
if (shouldForceConservativeGC()) {
  Heap::collectGarbage(ThreadState::HeapPointersOnStack,
ThreadState::GCWithoutSweep);
} else if (shouldSchedulePreciseGC())
  ...

[sof, 2015/02/20 09:33:49]

See above; redundant.

+        // If GC is deemed urgent, eagerly sweep and finalize any external allocations right away.
+        GCType gcType = Heap::isGCUrgentlyRequested() ? GCWithSweep : GCWithoutSweep;
+        Heap::clearUrgentGC();
+        Heap::collectGarbage(HeapPointersOnStack, gcType);
+        return;
+    }
+    if (shouldSchedulePreciseGC())
         schedulePreciseGC();
     else if (shouldScheduleIdleGC())
         scheduleIdleGC();
 }
 
 void ThreadState::performIdleGC(double deadlineSeconds)
 {
     ASSERT(isMainThread());
 
     m_hasPendingIdleTask = false;
@@ skipping 611 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