[heap] Synchronize young generation GC with concurrent marking.

src/heap/concurrent-marking.cc

 // Copyright 2017 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/heap/concurrent-marking.h"
 
 #include <stack>
 #include <unordered_map>
 
 #include "src/heap/concurrent-marking-deque.h"
@@ skipping 167 matching lines @@
   STATIC_ASSERT(!(V8_CONCURRENT_MARKING && V8_DOUBLE_FIELDS_UNBOXING));
   // The runtime flag should be set only if the compile time flag was set.
   CHECK(!FLAG_concurrent_marking || V8_CONCURRENT_MARKING);
 }
 
 ConcurrentMarking::~ConcurrentMarking() { delete visitor_; }
 
 void ConcurrentMarking::Run() {
   double time_ms = heap_->MonotonicallyIncreasingTimeInMs();
   size_t bytes_marked = 0;
+  base::Mutex* relocation_mutex = heap_->relocation_mutex();
   {
     TimedScope scope(&time_ms);
     HeapObject* object;
     while ((object = deque_->Pop(MarkingThread::kConcurrent)) != nullptr) {
+      base::LockGuard<base::Mutex> guard(relocation_mutex);
       bytes_marked += visitor_->Visit(object);
     }
   }
   if (FLAG_trace_concurrent_marking) {
     heap_->isolate()->PrintWithTimestamp("concurrently marked %dKB in %.2fms\n",
                                          static_cast<int>(bytes_marked / KB),
                                          time_ms);
   }
 }
 
@@ skipping 12 matching lines @@
 }
 
 void ConcurrentMarking::EnsureTaskCompleted() {
   if (IsTaskPending()) {
     WaitForTaskToComplete();
   }
 }
 
 }  // namespace internal
 }  // namespace v8