*** old/src/share/vm/utilities/workgroup.cpp	Tue Dec  9 14:42:33 2014
--- new/src/share/vm/utilities/workgroup.cpp	Tue Dec  9 14:42:33 2014

*** 44,54 ****
--- 44,55 ----
           "They cannot both be STW GC and Concurrent threads" );
  
    // Other initialization.
    _monitor = new Monitor(/* priority */       Mutex::leaf,
                           /* name */           "WorkGroup monitor",
!                          /* allow_vm_block */ are_GC_task_threads);
!                          /* allow_vm_block */ are_GC_task_threads,
+                                               Monitor::_safepoint_check_sometimes);
    assert(monitor() != NULL, "Failed to allocate monitor");
    _terminate = false;
    _task = NULL;
    _sequence_number = 0;
    _started_workers = 0;

*** 376,391 ****
--- 377,393 ----
  
  
  // *** WorkGangBarrierSync
  
  WorkGangBarrierSync::WorkGangBarrierSync()
-   : _monitor(Mutex::safepoint, "work gang barrier sync", true),
+              Monitor::_safepoint_check_never),
      _n_workers(0), _n_completed(0), _should_reset(false), _aborted(false) {
  }
  
  WorkGangBarrierSync::WorkGangBarrierSync(uint n_workers, const char* name)
!   : _monitor(Mutex::safepoint, name, true, Monitor::_safepoint_check_never),
      _n_workers(n_workers), _n_completed(0), _should_reset(false), _aborted(false) {
  }
  
  void WorkGangBarrierSync::set_n_workers(uint n_workers) {
    _n_workers    = n_workers;