public static ExecutorService createBackgroundExecutor(){
  final ExecutorService executor=Executors.newSingleThreadExecutor(new DaemonThreadFactory(DEFAULT_BACKGROUND_EXECUTOR_NAME));
  BACKGROUND_EXECUTORS.add(executor);
  return executor;
}

public static ExecutorService createBackgroundExecutor ( ) { final ExecutorService executor = Executors . newSingleThreadExecutor ( new DaemonThreadFactory ( DEFAULT_BACKGROUND_EXECUTOR_NAME ) ) ; BACKGROUND_EXECUTORS . add ( executor ) ; return executor ; }
creates a single - threaded executor that is registered by this class in order to shut it down later ( when it becomes necessary ) .
