Add flag to control background finalization.

runtime/vm/scavenger.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/scavenger.h"
 
 #include "vm/dart.h"
 #include "vm/dart_api_state.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
@@ skipping 798 matching lines @@
     StackZone zone(thread);
     // Setup the visitor and run the scavenge.
     ScavengerVisitor visitor(isolate, this, from);
     page_space->AcquireDataLock();
     IterateRoots(isolate, &visitor);
     int64_t start = OS::GetCurrentTimeMicros();
     ProcessToSpace(&visitor);
     int64_t middle = OS::GetCurrentTimeMicros();
     {
       TIMELINE_FUNCTION_GC_DURATION(thread, "WeakHandleProcessing");
-      FinalizationQueue* queue = new FinalizationQueue();
-      ScavengerWeakVisitor weak_visitor(thread, this, queue);
-      IterateWeakRoots(isolate, &weak_visitor);
-      if (queue->length() > 0) {
-        Dart::thread_pool()->Run(new BackgroundFinalizer(isolate, queue));
+      if (FLAG_background_finalization) {
+        FinalizationQueue* queue = new FinalizationQueue();
+        ScavengerWeakVisitor weak_visitor(thread, this, queue);
+        IterateWeakRoots(isolate, &weak_visitor);
+        if (queue->length() > 0) {
+          Dart::thread_pool()->Run(new BackgroundFinalizer(isolate, queue));
+        } else {
+          delete queue;
+        }
       } else {
-        delete queue;
+        ScavengerWeakVisitor weak_visitor(thread, this, NULL);
+        IterateWeakRoots(isolate, &weak_visitor);
       }
     }
     ProcessWeakReferences();
     page_space->ReleaseDataLock();
 
     // Scavenge finished. Run accounting.
     int64_t end = OS::GetCurrentTimeMicros();
     heap_->RecordTime(kProcessToSpace, middle - start);
     heap_->RecordTime(kIterateWeaks, end - middle);
     stats_history_.Add(
@@ skipping 58 matching lines @@
 }
 
 
 void Scavenger::FreeExternal(intptr_t size) {
   ASSERT(size >= 0);
   external_size_ -= size;
   ASSERT(external_size_ >= 0);
 }
 
 }  // namespace dart