src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

*** 1543,1553 ****
--- 1543,1557 ----
    // We need to reset the concurrency level before each
    // proxy task execution, so that the termination protocol
    // and overflow handling in G1CMTask::do_marking_step() knows
    // how many workers to wait for.
    _cm->set_concurrency(ergo_workers);
+   if (ergo_workers == 1) {
+     proc_task_proxy.work(0);
+   } else {
      _workers->run_task(&proc_task_proxy, ergo_workers);
+   }
  }
  
  void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) {
    ResourceMark rm;
    HandleMark   hm;