Wait for sweeper threads and finalize sweeping only if parallel/concurrent sweeping was in progress.

src/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2527 matching lines @@
 
     allocation_info_.top = NULL;
     allocation_info_.limit = NULL;
   }
 }
 
 
 bool PagedSpace::EnsureSweeperProgress(intptr_t size_in_bytes) {
   MarkCompactCollector* collector = heap()->mark_compact_collector();
   if (collector->AreSweeperThreadsActivated()) {
-    if (FLAG_concurrent_sweeping) {
+    if (collector->IsConcurrentSweepingInProgress()) {
       if (collector->StealMemoryFromSweeperThreads(this) < size_in_bytes) {
         collector->WaitUntilSweepingCompleted();
         collector->FinalizeSweeping();
         return true;
       }
       return false;
     }
     return true;
   } else {
     return AdvanceSweeper(size_in_bytes);
@@ skipping 563 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal