Wait for sweeper threads when a scan on scavenge page is not swept.

src/mark-compact.h

 // 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.
 
 #ifndef V8_MARK_COMPACT_H_
 #define V8_MARK_COMPACT_H_
 
 #include "src/compiler-intrinsics.h"
 #include "src/spaces.h"
 
@@ skipping 640 matching lines @@
 
   bool abort_incremental_marking() const { return abort_incremental_marking_; }
 
   bool is_compacting() const { return compacting_; }
 
   MarkingParity marking_parity() { return marking_parity_; }
 
   // Concurrent and parallel sweeping support. If required_freed_bytes was set
   // to a value larger than 0, then sweeping returns after a block of at least
   // required_freed_bytes was freed. If required_freed_bytes was set to zero
-  // then the whole given space is swept.
+  // then the whole given space is swept. It returns the size of the maximum
+  // continuous freed memory chunk.
   int SweepInParallel(PagedSpace* space, int required_freed_bytes);
 
+  // Sweeps a given page concurrently to the sweeper threads. It returns the
+  // size of the maximum continuous freed memory chunk.
+  int SweepInParallel(Page* page, PagedSpace* space);
+
   void EnsureSweepingCompleted();
 
   // If sweeper threads are not active this method will return true. If
   // this is a latency issue we should be smarter here. Otherwise, it will
   // return true if the sweeper threads are done processing the pages.
   bool IsSweepingCompleted();
 
   void RefillFreeList(PagedSpace* space);
 
   bool AreSweeperThreadsActivated();
@@ skipping 304 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_