Wait for sweeper threads when verifying the heap.

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 4506 matching lines @@
 }
 
 
 #ifdef VERIFY_HEAP
 void Heap::Verify() {
   CHECK(HasBeenSetUp());
   HandleScope scope(isolate());
 
   store_buffer()->Verify();
 
+  if (mark_compact_collector()->sweeping_in_progress()) {
+    // We have to wait here for the sweeper threads to have an iterable heap.
+    mark_compact_collector()->EnsureSweepingCompleted();
+  }
+
   VerifyPointersVisitor visitor;
   IterateRoots(&visitor, VISIT_ONLY_STRONG);
 
   VerifySmisVisitor smis_visitor;
   IterateSmiRoots(&smis_visitor);
 
   new_space_.Verify();
 
   old_pointer_space_->Verify(&visitor);
   map_space_->Verify(&visitor);
@@ skipping 1903 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