Wait for sweeper threads in incremental marking step when sweeper threads are done sweeping.

src/incremental-marking.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 "v8.h"
 
 #include "incremental-marking.h"
 
 #include "code-stubs.h"
 #include "compilation-cache.h"
@@ skipping 868 matching lines @@
   bytes_scanned_ += bytes_to_process;
 
   double start = 0;
 
   if (FLAG_trace_incremental_marking || FLAG_trace_gc ||
       FLAG_print_cumulative_gc_stat) {
     start = OS::TimeCurrentMillis();
   }
 
   if (state_ == SWEEPING) {
+    if (heap_->mark_compact_collector()->IsConcurrentSweepingInProgress() &&
+        heap_->mark_compact_collector()->IsSweepingCompleted()) {
+      heap_->mark_compact_collector()->WaitUntilSweepingCompleted();
+    }
     if (!heap_->mark_compact_collector()->IsConcurrentSweepingInProgress()) {
       bytes_scanned_ = 0;
       StartMarking(PREVENT_COMPACTION);
     }
   } else if (state_ == MARKING) {
     ProcessMarkingDeque(bytes_to_process);
     if (marking_deque_.IsEmpty()) MarkingComplete(action);
   }
 
   steps_count_++;
@@ skipping 89 matching lines @@
   bytes_scanned_ = 0;
   write_barriers_invoked_since_last_step_ = 0;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
 }
 
 } }  // namespace v8::internal