CODEWITHSUNDEEP
javaconcurrencyscheduling
miah
miah

Reputation: 8609

Checking if periodic ScheduledFuture is running now

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?

Upvotes: 3

Views: 6582

Answers (3)

Bogdan Samondros
Bogdan Samondros

Reputation: 158

If you need to check non-periodic future (java.util.concurrent.FutureTask) the solution with only

future.getDelay(TimeUnit.MILLISECONDS) <= 0

doesn't work. You can't even combine

future.getDelay(TimeUnit.MILLISECONDS) <= 0 && !future.isDone()

because future.isDone() returns true for all states except NEW which means "Scheduled". But if future is just started future.getDelay(TimeUnit.MILLISECONDS) <= 0 && !future.isDone() never return true because not started future (NEW) never has negative delay

So I came up with pretty stupid simple solution and it works

future.isDone() && future.toString().startsWith("[Not completed]")

It's a bit ugly but does the job

Upvotes: 0

miah
miah

Reputation: 8609

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.

Upvotes: 8

Christian Kuetbach
Christian Kuetbach

Reputation: 16060

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.

Upvotes: 2

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