private boolean executorAlive(ExecutorService tpe, String name) {
    if (tpe == null) {
      return false;
    } else {
      int ac = ((ThreadPoolExecutor) tpe).getActiveCount();
      // boolean result = tpe.getActiveCount() > 0;
      if (ac > 0) {
        if (logger.isDebugEnabled()) {
          logger.debug("Still waiting for {} threads in '{}' pool to exit", ac, name);
        }
        return true;
      } else {
        return false;
      }
    }
  }
returns the serialThread's queue if throttling is being used, null if not
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterOperationExecutors.java