Race condition in TimerTask KillThread test

David Holmes david.holmes at oracle.com
Mon Nov 7 01:46:25 UTC 2011

On 5/11/2011 8:37 AM, Alan Bateman wrote:
> On 04/11/2011 15:52, Gary Adams wrote:
>> :
>> I'll attempt a simple fix for the KillThread case by replacing :
>> Thread.sleep(100);
>> with a simple loop
>> do {
>> Thread.sleep(100);
>> } while (waiting);
>> where the TimerTask runnable will clear the flag
>> with "waiting = false " once it has been launched.
> I don't think this will guarantee that the timer thread will have
> terminated before the main thread schedules the second event. I think
> this test would be robust if you capture a reference to the timer thread
> in the first task and have the main thread wait or poll until it has a
> reference to the thread. Once it has a reference to the thread then it
> can wait for it to terminate before attempting to schedule the second task.

Agreed. As soon as waiting is set we can switch back to the main thread 
and proceed to the next phase of the test - but the timer thread is 
still alive at that point. If the issue is checking for thread 
termination then we must track that directly.


> -Alan.

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