Problem with while stop thread

Question

I am trying to stop a thread. while stopping my thread i got thread interrupted exception.

What I can do if thread throw interrupted exception. should i catch it and do nothing or do i need to do anything?

"Its depends" is my first reaction. Some more context please? — Pavan, Jun 08 '11 at 16:45
Take a look at this Brian Goetz article http://www.ibm.com/developerworks/java/library/j-jtp05236/index.html — Steve Kuo, Jun 08 '11 at 18:14

Vincent Koeman · Answer 1 · 2011-06-09T08:22:02.573

4

You should not 'just stop' a thread. The thing I mostly do is create a public (perhaps static) variable in the Thread's class that indicates when the thread should stop. So something like a declaration of

public volatile bool shouldStop = false;

Then, at the end of every cycle of your thread, you could check if you need to quit (break from the while-loop or something).

Threads can be very annoying to handle! Calling interrupt/stop functions on just a thread itself is possible, but mostly unwanted.

edited Jun 09 '11 at 08:22

answered Jun 08 '11 at 16:45

Vincent Koeman

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to me, it makes more sense to just check the thread's interrupted state (i.e. `Thread.currentThread().isInterrupted()`) – mre Jun 08 '11 at 16:52
3

It might be better to make that a _volatile_ boolean. – Paul Cager Jun 08 '11 at 17:27
Why is calling interrupt unwanted? It's the proper mechanism to interrupt a waiting thread. – Steve Kuo Jun 08 '11 at 18:37
If the code is throwing an InterruptedException, then it is blocking on something. The only way to cancel the blocking is to interrupt the thread. If it is an operation that will timeout or complete, then the code would have to wait for that to happen before it can check the shouldStop flag, which may not be acceptable – Michael Krussel Jun 08 '11 at 18:45

score 2 · Answer 2 · answered Jun 08 '11 at 16:46

There is a reason .stop() and .suspend() were deprecated and should not be used. This article is relevant: http://download.oracle.com/javase/1.4.2/docs/guide/misc/threadPrimitiveDeprecation.html

Also I quote the Javadocs:

Deprecated. This method is inherently unsafe. Stopping a thread with Thread.stop causes it to unlock all of the monitors that it has locked (as a natural consequence of the unchecked ThreadDeath exception propagating up the stack). If any of the objects previously protected by these monitors were in an inconsistent state, the damaged objects become visible to other threads, potentially resulting in arbitrary behavior. Many uses of stop should be replaced by code that simply modifies some variable to indicate that the target thread should stop running. The target thread should check this variable regularly, and return from its run method in an orderly fashion if the variable indicates that it is to stop running. If the target thread waits for long periods (on a condition variable, for example), the interrupt method should be used to interrupt the wait. For more information, see Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?.

You should find some way (whether by some shared variable or otherwise) to synchronise your threads so the thread can end itself.

This is a good point, but I don't think OP is using .stop(). Otherwise, they wouldn't be getting the InterruptedException. — Tom, Jun 08 '11 at 16:49

score 1 · Answer 3 · edited May 23 '17 at 12:20

It depends on your needs. You can (for example) do something like this:

public void run() {
    try {
         // do thread stuff
    } catch(ThreadInterruptedException ex) {
         // close gracefully what needed to be closed
    }
}

But the stop method is deprecated. So a better solution is to put some boolean variable to indicate whether the thread should stop or not and provide a method to change it in order to stop the thread (see this question for example).

Problem with while stop thread

3 Answers3