Java Timer vs ExecutorService?

java timer scheduled-tasks scheduling executorservice
kal picture kal · Jan 3, 2009 · Viewed 109.1k times · Source

I have code where I schedule a task using java.util.Timer. I was looking around and saw ExecutorService can do the same. So this question here, have you used Timer and ExecutorService to schedule tasks, what is the benefit of one using over another?

Also wanted to check if anyone had used the Timer class and ran into any issues which the ExecutorService solved for them.

Answer

Peter Štibraný picture Peter Štibraný · Jan 3, 2009

According to Java Concurrency in Practice:

  • Timer can be sensitive to changes in the system clock, ScheduledThreadPoolExecutor isn't.
  • Timer has only one execution thread, so long-running task can delay other tasks. ScheduledThreadPoolExecutor can be configured with any number of threads. Furthermore, you have full control over created threads, if you want (by providing ThreadFactory).
  • Runtime exceptions thrown in TimerTask kill that one thread, thus making Timer dead :-( ... i.e. scheduled tasks will not run anymore. ScheduledThreadExecutor not only catches runtime exceptions, but it lets you handle them if you want (by overriding afterExecute method from ThreadPoolExecutor). Task which threw exception will be canceled, but other tasks will continue to run.

If you can use ScheduledThreadExecutor instead of Timer, do so.

One more thing... while ScheduledThreadExecutor isn't available in Java 1.4 library, there is a Backport of JSR 166 (java.util.concurrent) to Java 1.2, 1.3, 1.4, which has the ScheduledThreadExecutor class.

Related questions

How to use Timer class to call a method, do something, reset timer, repeat?

I'm a Java beginner and have been futzing around with various solutions to this problem and have gotten myself kind of knotted up. I've tried with Threads and then discovered this Timer class and have messed around with it without …

Read More
How i can run my TimerTask everyday 2 PM

I want to execute a job everyday 2PM . Which method of java.util.Timer i can use to schedule my job? After 2Hrs Run it will stop the job and reschedule for next day 2PM.

Read More
Android Timer schedule vs scheduleAtFixedRate

I'm writing an Android application that records audio every 10 minutes. I am using a Timer to do that. But what is the difference between schedule and scheduleAtFixedRate? Is there any performance benefit in using one over the other?

Read More