Remove a thread-local termination GC

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:
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  *     * Redistributions of source code must retain the above copyright
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  *     * Redistributions in binary form must reproduce the above
@@ skipping 212 matching lines @@
 
   // Finish sweeping.
   completeSweep();
 
   releaseStaticPersistentNodes();
 
   // From here on ignore all conservatively discovered
   // pointers into the heap owned by this thread.
   m_isTerminating = true;
 
   // Set the terminate flag on all heap pages of this thread. This is used to

[sof, 2017/02/08 11:49:47]

Could you make this comment up-to-date at the same time?

[haraken, 2017/02/08 12:00:10]

Maybe can I remove prepareForThreadStateTermination() in a follow-up after I've
confirmed this CL works on ToT? Added a TODO.

   // ensure we don't trace pages on other threads that are not part of the
   // thread local GC.
   prepareForThreadStateTermination();
 
   ProcessHeap::crossThreadPersistentRegion().prepareForThreadStateTermination(
       this);
 
   // Do thread local GC's as long as the count of thread local Persistents
   // changes and is above zero.
   int oldCount = -1;
   int currentCount = getPersistentRegion()->numberOfPersistents();
   ASSERT(currentCount >= 0);
   while (currentCount != oldCount) {
-    collectGarbageForTerminatingThread();
+    collectGarbage(BlinkGC::NoHeapPointersOnStack, BlinkGC::GCWithSweep,

[sof, 2017/02/08 11:49:47]

We're unnecessarily locking CTP access by doing this, and risk compacting --
what about the extra heap stat accounting done?

[haraken, 2017/02/08 12:00:10]

Added BlinkGC::ThreadTerminationGC. This prevents the GC from triggering a heap
compaction. See HeapCompact::shouldCompact().

I think we need to lock CTP though.

+                   BlinkGC::PreciseGC);
     // Release the thread-local static persistents that were
     // instantiated while running the termination GC.
     releaseStaticPersistentNodes();
     oldCount = currentCount;
     currentCount = getPersistentRegion()->numberOfPersistents();
   }
   // We should not have any persistents left when getting to this point,
   // if we have it is probably a bug so adding a debug ASSERT to catch this.
   ASSERT(!currentCount);
   // All of pre-finalizers should be consumed.
@@ skipping 1523 matching lines @@
     collectGarbage(BlinkGC::NoHeapPointersOnStack, BlinkGC::GCWithSweep,
                    BlinkGC::ForcedGC);
     size_t liveObjects = heap().heapStats().markedObjectSize();
     if (liveObjects == previousLiveObjects)
       break;
     previousLiveObjects = liveObjects;
   }
 }
 
 }  // namespace blink