Java Concurrent Execution of Thread Task

Question

I have a task that needs to be executed on a schedule. (It basically polls a database looking for a change and then executes code depending on the result). The problem is that I need the polled task to happen even when it is already executing.

So far I have tried using a Timer/TimerTask combo with the scheduleAtFixedRate() method and the ScheduledThreadPoolExecutor/Thread combo with the scheduleAtFixedRate() method.

Both wait for the current scheduled task to complete before running the next. I need to be able to schedule a task to run every 5 seconds and have it run even if the last execution of the task has not yet completed.

Any ideas?

Answer 1

How about using one Timer as the "kick-off" timer, but then a separate thread pool for execution: when the timer ticks, you submit the task to the thread pool for immediate execution. (You may want to tweak the thread pool to have some maximum number of tasks running simultaneously.)