Apache-worker stuck at 100% CPU
Alfred Perlstein
alfred at freebsd.org
Fri Sep 12 17:15:55 UTC 2008
* Ivan Voras <ivoras at freebsd.org> [080912 04:09] wrote:
> Hi,
>
> I'm running apache2.2.9-worker without mod_php (with mod_fcgid and PHP
> as FastCGI) and a process or a thread repeatedly gets stuck:
>
> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
> 5503 www 41 96 0 50820K 30960K umtxn 0 722:42 99.32% httpd
>
> It doesn't use sys time and ktrace doesn't record anything.
>
> Any clues where to dig next?
>
> I'm not using any unusual modules for apache, and the same configuration
> worked in 6.3 (this system was upgraded from 6.3 to 7.0-R - I checked
> that all apache dependancies are compiled for 7.0).
Try using "pstack" a few times. It's in ports.
Also, gcore(1) might help.
You can also try to attach using gdb.
Basically, one of these tools should give you a stack trace which
can help.
It's interesting that the process is in "umtxn" though, is it
multithreaded apache? Can you dump the threads? I think top(1)
has an option to view each thread, how about trying that?
thank you,
-Alfred
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