Apache-worker stuck at 100% CPU
ivoras at freebsd.org
Fri Sep 12 22:16:39 UTC 2008
2008/9/12 Alfred Perlstein <alfred at freebsd.org>:
> Try using "pstack" a few times. It's in ports.
> Also, gcore(1) might help.
> You can also try to attach using gdb.
I did, but either I'm missing something or I'm not using it well,
because I can't get a backtrace. How do I select threads to backtrace?
How do I pick what thread to backtrace?
> 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?
Yes, it's multithreaded apache. This did help somewhat - when I do it
I see that it's not actually stuck in umtxn - there's one thread that
consumes the CPU and it's apparently always running (in state CPUx).
PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND
7212 www 103 0 30340K 7932K CPU2 2 444:23 99.02% httpd
I'm currently upgrading the system to 7-STABLE, to see if it helps.
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