Checking if periodic ScheduledFuture is running now

问题

I have a periodic task scheduled via Spring TaskScheduler.schedule(Runnable, Trigger).

Given the returned ScheduledFuture, is there any way to check, if the task is running at current moment?

回答1:

You can change you Runnable like this:

class Runner implements Runnable{
    public volatile boolean RUNNING = false;
        public void run(){

        RUNNING = true;
        try{
            // Your code
        } finally {
            RUNNING = false;
        }
    }
}

edit Thought operations with boolean are atomic and don't need to be volatile.

回答2:

After a bit of testing,

public static boolean isRunning(ScheduledFuture future) {
    return future.getDelay(TimeUnit.MILLISECONDS) <= 0;
}

works like a charm. Seems the task gets rescheduled only after completion, so getDelay() returns negative value.

来源：https://stackoverflow.com/questions/4814916/checking-if-periodic-scheduledfuture-is-running-now