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javaexecutorserviceshutdownfinalize

ExecutorService shutdown in finalize()

I've got a class which manages a cache of objects.
The cache is cleaned once an hour via ScheduledExecutorService.
Is it ok to shutdown the ExecutorService via the class finalize() method?

@Override
protected void finalize() throws Throwable {
    EXECUTOR_SERVICE.shutdownNow();
}

I'm currently running on Java 6.

Solution

  • There is no "call-this-last" method in Java. The finalize method is actually a "eat-memory-and-maybe-don't-even-call-me" method in Java.

    The ExecutorService has shutdown and a shutdownNow. Use these, but not in a finalize method.

    Call shutdown when your app knows that it "wants to stop soonish". Call shutdownNow when your app knows that it "wants to stop asap, but maybe not immediately`.

    There is no way to instruct the ExecutorService to "stop now, don't wait".

    Here is a Brief ExecutorService Tutorial on Baeldung.