RFR 8145127: VM warning: WaitForMultipleObjects timed out (0) ...

David Holmes david.holmes at oracle.com
Tue Dec 15 06:31:23 UTC 2015

I really wish we had some view inside windows to see exactly what is 
going wrong here. :(

On 15/12/2015 12:09 AM, Ivan Gerasimov wrote:
> Hello!
> There was a timeout observed in os_windows.cpp at the line
> 3945           res = WaitForMultipleObjects(MAXIMUM_WAIT_OBJECTS,
> handles, FALSE, EXIT_TIMEOUT);
> This means there were more than 64 threads exiting at the same time and
> none of the first 64 threads could make any progress during 5 minutes.
> Sigh.
> To address this issue I suggest two things:
> 1)
> Increase the size of the queue of exiting threads.
> We'll still have to wait for only the first 64 threads, if the queue is
> exhausted.
> But the chances we hit this condition are greatly reduced.
> 2)
> Raise process_exiting flag earlier, i.e. before trying to enter the
> critical section.
> This should decrease the number of threads, contending for a slot in the
> 'handles' array during the process exit.
> Additionally, it is proposed to suspend all the threads, but the one
> which raised the flag 'process_exiting'.
> It would be important in a case, when two threads are about to call
> exit() concurrently.
> Otherwise, a race could be faced, if the first thread is waiting for all
> the registered handles, while the second one skips the critical section
> altogether and calls ::exit().
> Build went fine on all platforms.  The JTREG tests from 'hotspot' subset
> all pass.
> Would you please help review the proposed fix?
> BUGURL: https://bugs.openjdk.java.net/browse/JDK-8145127
> WEBREV: http://cr.openjdk.java.net/~igerasim/8145127/00/webrev/

Can't quite get my head round the whole strategy, but in this loop:

4033       while (pr_ex != curr_id) {

pr_ex is never updated!


> Sincerely yours,
> Ivan

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