Add flag to control background finalization.

runtime/vm/gc_marker.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/gc_marker.h"
 
 #include "vm/allocation.h"
 #include "vm/dart_api_state.h"
 #include "vm/isolate.h"
 #include "vm/log.h"
@@ skipping 690 matching lines @@
     if (num_tasks == 0) {
       // Mark everything on main thread.
       SkippedCodeFunctions* skipped_code_functions =
           collect_code ? new(zone) SkippedCodeFunctions() : NULL;
       UnsyncMarkingVisitor mark(isolate, heap_, page_space, &marking_stack,
                                 skipped_code_functions);
       IterateRoots(isolate, &mark, 0, 1);
       mark.DrainMarkingStack();
       {
         TIMELINE_FUNCTION_GC_DURATION(thread, "WeakHandleProcessing");
-        FinalizationQueue* queue = new FinalizationQueue();
-        MarkingWeakVisitor mark_weak(thread, queue);
-        IterateWeakRoots(isolate, &mark_weak);
-        if (queue->length() > 0) {
-          Dart::thread_pool()->Run(new BackgroundFinalizer(isolate, queue));
+        if (FLAG_background_finalization) {
+          FinalizationQueue* queue = new FinalizationQueue();
+          MarkingWeakVisitor mark_weak(thread, queue);
+          IterateWeakRoots(isolate, &mark_weak);
+          if (queue->length() > 0) {
+            Dart::thread_pool()->Run(new BackgroundFinalizer(isolate, queue));
+          } else {
+            delete queue;
+          }
         } else {
-          delete queue;
+          MarkingWeakVisitor mark_weak(thread, NULL);
+          IterateWeakRoots(isolate, &mark_weak);
         }
       }
       // All marking done; detach code, etc.
       FinalizeResultsFrom(&mark);
     } else {
       ThreadBarrier barrier(num_tasks + 1,
                             heap_->barrier(),
                             heap_->barrier_done());
       // Used to coordinate draining among tasks; all start out as 'busy'.
       uintptr_t num_busy = num_tasks;
@@ skipping 16 matching lines @@
         // Note: we need to have two barriers here because we want all markers
         // and main thread to make decisions in lock step.
         barrier.Sync();
         more_to_mark = AtomicOperations::LoadRelaxed(&num_busy) > 0;
         barrier.Sync();
       } while (more_to_mark);
 
       // Phase 2: Weak processing on main thread.
       {
         TIMELINE_FUNCTION_GC_DURATION(thread, "WeakHandleProcessing");
-        FinalizationQueue* queue = new FinalizationQueue();
-        MarkingWeakVisitor mark_weak(thread, queue);
-        IterateWeakRoots(isolate, &mark_weak);
-        if (queue->length() > 0) {
-          Dart::thread_pool()->Run(new BackgroundFinalizer(isolate, queue));
+        if (FLAG_background_finalization) {
+          FinalizationQueue* queue = new FinalizationQueue();
+          MarkingWeakVisitor mark_weak(thread, queue);
+          IterateWeakRoots(isolate, &mark_weak);
+          if (queue->length() > 0) {
+            Dart::thread_pool()->Run(new BackgroundFinalizer(isolate, queue));
+          } else {
+            delete queue;
+          }
         } else {
-          delete queue;
+          MarkingWeakVisitor mark_weak(thread, NULL);
+          IterateWeakRoots(isolate, &mark_weak);
         }
       }
       barrier.Sync();
 
       // Phase 3: Finalize results from all markers (detach code, etc.).
       barrier.Exit();
     }
     ProcessWeakTables(page_space);
     ProcessObjectIdTable(isolate);
   }
   Epilogue(isolate, invoke_api_callbacks);
 }
 
 }  // namespace dart