Wait for sweeper threads in EnsureSweeperProgress() only if the main thread finished its sweeping p…

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index b5d60fd41e80f81f5395dff0ee0f665dc161c8d2..1c508fe2a8fea191a6b8de047c396a1aab7e9596 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -698,6 +698,14 @@ class MarkCompactCollector {
 
   void FinalizeSweeping();
 
+  void set_sequential_sweeping(bool sequential_sweeping) {
+    sequential_sweeping_ = sequential_sweeping;
+  }
+
+  bool sequential_sweeping() const {
+    return sequential_sweeping_;
+  }
+
   // Parallel marking support.
   void MarkInParallel();
 
@@ -749,6 +757,8 @@ class MarkCompactCollector {
   // True if concurrent or parallel sweeping is currently in progress.
   bool sweeping_pending_;
 
+  bool sequential_sweeping_;
+
   // A pointer to the current stack-allocated GC tracer object during a full
   // collection (NULL before and after).
   GCTracer* tracer_;
@@ -904,6 +914,22 @@ class MarkCompactCollector {
 };
 
 
+class SequentialSweepingScope BASE_EMBEDDED {
+ public:
+  explicit SequentialSweepingScope(MarkCompactCollector *collector) :
+    collector_(collector) {
+    collector_->set_sequential_sweeping(true);
+  }
+
+  ~SequentialSweepingScope() {
+    collector_->set_sequential_sweeping(false);
+  }
+
+ private:
+  MarkCompactCollector* collector_;
+};
+
+
 const char* AllocationSpaceName(AllocationSpace space);
 
 } }  // namespace v8::internal