code: public void shutdown() {
          executorservice.shutdown();
          try {
              executorservice.awaitTermination(Long.MAX_VALUE, TimeUnit.MINUTES);
          } catch (InterruptedException e) {
              throw new KumoException("Executor awaitTermination was interrupted, consider manual termination", e);
          }
      }
docs: Signals the ExecutorService to shutdown and await Termination.<br>
  This is a blocking call.