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I have a program for which I plan to use a lot of Timer objects, and as I understand it each Timer runs on it's own thread. So I wondered if it's possible to start so many Timers that it hurts the performance of the program with too many threads.

For example, I was thinking of having several (boolean, Timer) pairs to have booleans that invert at several different time intervals.

HahaHortness
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2 Answers2

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Yes, Timer objects do consume thread resources, so it is possible to hit a limit within the JVM. If your goal is to schedule tasks to run at various points in time, you might want to look at one of the many Java ExecutorService implementations such as ScheduledThreadPoolExecutor. The Executors class provides a convenient factory for generating these objects. Several implementations utilize thread pools, which you can configure to determine how many tasks may run simultaneously. You can also consume output that the tasks produce (if any) and shutdown the tasks in an orderly fashion if your program needs to exit.

Rob H
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  • From Java 1.5, ScheduledExecutorServie is the recommended way to schedule timed tasks. It depends on what you do but personally I think something like a few hundred thread (Timer) is the practical maximum. – Enno Shioji Mar 02 '11 at 03:03
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You can run more than one task on the same Timer. Depending on how cpu intensive the tasks are, you could use just one or a few Timer instances to manage all your tasks. or, as @Rob mentions, you can use a ScheduledThreadPoolExecutor.

jtahlborn
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