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Date: Mon, 15 Sep 2008 19:27:38 -0700
From: Alfred Perlstein <alfred@freebsd.org>
To: Ivan Voras <ivoras@freebsd.org>
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Cc: stable@freebsd.org, freebsd-threads@freebsd.org
Subject: Re: Apache-worker stuck at 100% CPU
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* Ivan Voras <ivoras@freebsd.org> [080915 16:05] wrote:
> 2008/9/13 Alfred Perlstein <alfred@freebsd.org>:
> 
> >> Yes, it's multithreaded apache. This did help somewhat - when I show threads in top
> >> 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.
> 
> It didn't help. Exactly the same symptom happened again. It looks like
> it happens a few days after the last system reboot. After it happens
> the first time, restarting Apache immediately produces one such
> "stuck" thread - it looks like some system state gets corrupted over
> time.
> 
> >> How do I pick what thread to backtrace in gdb?
> >
> > i think the command is 'info threads' or 'show
> > threads' then i think you just type
> > 'thread FOO' to select the thread.
> 
> Both commands don't work / don't exist. Any others?
> 
> (background: apache22-worker port, no mod_php, on 7.0 and 7-STABLE
> suddenly gets stuck at 100% CPU; the same setup worked on 6-STABLE.
> I'm looking for ideas)

I'm sorry, I really can't help at this point other than to look
through the documents myself to figure out how to do a backtrace/select
threads.

Give it a shot, and let us know and we can go further.

Apologies,
-Alfred