- Make sure to prepare all threads for GC.

runtime/vm/thread_registry.h

 // Copyright (c) 2015, 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.
 
 #ifndef VM_THREAD_REGISTRY_H_
 #define VM_THREAD_REGISTRY_H_
 
 #include "vm/globals.h"
 #include "vm/growable_array.h"
 #include "vm/isolate.h"
@@ skipping 38 matching lines @@
   // any pending rendezvous request (if none, returns immediately).
   void CheckSafepoint() {
     MonitorLocker ml(monitor_);
     CheckSafepointLocked();
   }
 
   bool AtSafepoint() const { return in_rendezvous_; }
   Thread* Schedule(Isolate* isolate, bool is_mutator, bool bypass_safepoint);
   void Unschedule(Thread* thread, bool is_mutator, bool bypass_safepoint);
   void VisitObjectPointers(ObjectPointerVisitor* visitor, bool validate_frames);
+  void PrepareForGC();
 
  private:
   void AddThreadToActiveList(Thread* thread);
   void RemoveThreadFromActiveList(Thread* thread);
   Thread* GetThreadFromFreelist(Isolate* isolate);
   void ReturnThreadToFreelist(Thread* thread);
 
   // Note: Lock should be taken before this function is called.
   void CheckSafepointLocked();
 
@@ skipping 24 matching lines @@
   intptr_t remaining_;    // Number of threads yet to reach their safepoint.
   int64_t round_;         // Counter, to prevent missing updates to remaining_
                           // (see comments in CheckSafepointLocked).
 
   DISALLOW_COPY_AND_ASSIGN(ThreadRegistry);
 };
 
 }  // namespace dart
 
 #endif  // VM_THREAD_REGISTRY_H_