Prevent excessive processing of weak maps while marking.

src/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
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@@ skipping 823 matching lines @@
   void MarkRoots(RootMarkingVisitor* visitor);
 
   // Mark the string table specially.  References to internalized strings from
   // the string table are weak.
   void MarkStringTable();
 
   // Mark objects in implicit references groups if their parent object
   // is marked.
   void MarkImplicitRefGroups();
 
-  // Mark all objects which are reachable due to host application
-  // logic like object groups or implicit references' groups.
-  void ProcessExternalMarking(RootMarkingVisitor* visitor);
-
   // Mark objects reachable (transitively) from objects in the marking stack
   // or overflowed in the heap.
   void ProcessMarkingDeque();
 
+  // Mark objects reachable (transitively) from objects in the marking stack
+  // or overflowed in the heap.  This respects references only considered in
+  // the final atomic marking pause including the following:
+  //    - Processing of objects reachable through Harmony WeakMaps.
+  //    - Objects reachable due to host application logic like object groups
+  //      or implicit references' groups.
+  void ProcessAtomicMarking(RootMarkingVisitor* visitor);

[Hannes Payer (out of office), 2013/06/04 16:29:58]

The function name may be confusing if we add concurrency to the marker. Can we
rename this method to something like ProccessWeakReferences()?

[Michael Starzinger, 2013/06/04 16:42:41]

Yep, I am not happy with the "atomic" in the name either. But also "weak" has a
different meaning internally. How about ProcessEphemerons()?

[Michael Starzinger, 2013/06/04 17:16:08]

Done, as discussed offline.

+
   // Mark objects reachable (transitively) from objects in the marking
   // stack.  This function empties the marking stack, but may leave
   // overflowed objects in the heap, in which case the marking stack's
   // overflow flag will be set.
   void EmptyMarkingDeque();
 
   // Refill the marking stack with overflowed objects from the heap.  This
   // function either leaves the marking stack full or clears the overflow
   // flag on the marking stack.
   void RefillMarkingDeque();
@@ skipping 92 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_