Wait for sweeper threads only if we have to.

src/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/once.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 1279 matching lines @@
   // Verify that there are no pointers to new space in spaces where we
   // do not expect them.
   VerifyNonPointerSpacePointersVisitor v(heap);
   HeapObjectIterator code_it(heap->code_space());
   for (HeapObject* object = code_it.Next();
        object != NULL; object = code_it.Next())
     object->Iterate(&v);
 
   // The old data space was normally swept conservatively so that the iterator
   // doesn't work, so we normally skip the next bit.
-  if (!heap->old_data_space()->was_swept_conservatively()) {
+  if (heap->old_data_space()->is_iterable()) {
     HeapObjectIterator data_it(heap->old_data_space());
     for (HeapObject* object = data_it.Next();
          object != NULL; object = data_it.Next())
       object->Iterate(&v);
   }
 }
 #endif  // VERIFY_HEAP
 
 
 void Heap::CheckNewSpaceExpansionCriteria() {
@@ skipping 2928 matching lines @@
   Struct* result;
   { AllocationResult allocation = Allocate(map, space);
     if (!allocation.To(&result)) return allocation;
   }
   result->InitializeBody(size);
   return result;
 }
 
 
 bool Heap::IsHeapIterable() {
-  return (!old_pointer_space()->was_swept_conservatively() &&
-          !old_data_space()->was_swept_conservatively() &&
+  return (old_pointer_space()->is_iterable() &&
+          old_data_space()->is_iterable() &&
           new_space_top_after_last_gc_ == new_space()->top());
 }
 
 
 void Heap::MakeHeapIterable() {
   ASSERT(AllowHeapAllocation::IsAllowed());
   if (!IsHeapIterable()) {
     CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
   ASSERT(IsHeapIterable());
@@ skipping 2182 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal