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Date:      Tue, 16 Sep 2008 01:04:47 +0200
From:      "Ivan Voras" <ivoras@freebsd.org>
To:        "Alfred Perlstein" <alfred@freebsd.org>
Cc:        stable@freebsd.org, freebsd-threads@freebsd.org
Subject:   Re: Apache-worker stuck at 100% CPU
Message-ID:  <9bbcef730809151604i28533745m286e7314810d0362@mail.gmail.com>
In-Reply-To: <20080912225251.GG16977@elvis.mu.org>
References:  <gadgrb$4uc$1@ger.gmane.org> <20080912165808.GE16977@elvis.mu.org> <9bbcef730809121444u34991c52m2cbc01a8ada47eb5@mail.gmail.com> <20080912225251.GG16977@elvis.mu.org>

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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)



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