Wait for sweeper threads in EnsureSweeperProgress() only if the main thread...

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

BUG=

Review URL: https://codereview.chromium.org/12462002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13830 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mark-compact.cc

@@ -67,6 +67,7 @@ MarkCompactCollector::MarkCompactCollector() :  // NOLINT
       compacting_(false),
       was_marked_incrementally_(false),
       sweeping_pending_(false),
+      sequential_sweeping_(false),
       tracer_(NULL),
       migration_slots_buffer_(NULL),
       heap_(NULL),
@@ -3885,7 +3886,7 @@ void MarkCompactCollector::SweepSpaces() {
   // the map space last because freeing non-live maps overwrites them and
   // the other spaces rely on possibly non-live maps to get the sizes for
   // non-live objects.
-
+  SequentialSweepingScope scope(this);
   SweepSpace(heap()->old_pointer_space(), how_to_sweep);
   SweepSpace(heap()->old_data_space(), how_to_sweep);
 

src/mark-compact.h

@@ -692,6 +692,14 @@ 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();
 
@@ -743,6 +751,8 @@ 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_;
@@ -898,6 +908,22 @@ 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

src/spaces.cc

@@ -2553,9 +2553,11 @@ bool PagedSpace::EnsureSweeperProgress(intptr_t size_in_bytes) {
   if (collector->AreSweeperThreadsActivated()) {
     if (collector->IsConcurrentSweepingInProgress()) {
       if (collector->StealMemoryFromSweeperThreads(this) < size_in_bytes) {
-        collector->WaitUntilSweepingCompleted();
-        collector->FinalizeSweeping();
-        return true;
+        if (!collector->sequential_sweeping()) {
+          collector->WaitUntilSweepingCompleted();
+          collector->FinalizeSweeping();
+          return true;
+        }
       }
       return false;
     }

src/spaces.h

@@ -1765,9 +1765,9 @@ class PagedSpace : public Space {
 
   bool AdvanceSweeper(intptr_t bytes_to_sweep);
 
-  // When parallel sweeper threads are active this function waits
-  // for them to complete, otherwise AdvanceSweeper with size_in_bytes
-  // is called.
+  // When parallel sweeper threads are active and the main thread finished
+  // its sweeping phase, this function waits for them to complete, otherwise
+  // AdvanceSweeper with size_in_bytes is called.
   bool EnsureSweeperProgress(intptr_t size_in_bytes);
 
   bool IsLazySweepingComplete() {