private void forceThreadsToStop() {
    executors.forceThreadsToStop();
    Thread th = memberEventThread;
    if (th != null) {
      clobberThread(th);
    }
  }
Wait for the ancillary queues to exit. Kills them if they are still around.
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterDistributionManager.java