code: public void schedulePrune(long delay) {
  		this.pruneJobFuture = GlobalPruneTimer.INSTANCE.schedule(new Runnable() {
  			@Override
  			public void run() {
  				prune();
  			}
  		}, delay);
  	}
docs: 定时清理
  
  @param delay 间隔时长，单位毫秒