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From Nick Kew <n...@webthing.com>
Subject Re: [users@httpd] Tons of Segfaults in Apache-Prefork 2.2.4
Date Thu, 17 Apr 2008 15:25:21 GMT
On Thu, 17 Apr 2008 12:13:04 +0200
Markus Meyer <markus.meyer@koeln.de> wrote:

> Hi all,
> 
> we experience a lot of threads segfaulting with our Apaches. There
> are about 300 dying threads per day. The error in syslog is the
> following:
> 
> Apr 16 23:51:41 foo-bar kernel: httpd[24629]: segfault at 
> 00007fffae529f98 rip 00002b2ffd6408b7 rsp 00007fffae529ea0 error 6
> 
> I wish I could give you some kind of trace or core file. But we don't 
> get a core file since only threads die and not the root-process. I

Hmmm?  Your subject line says prefork.  With prefork, there are
no threads.  Anyway, no matter.

You should get cores from a segfault.  Have you enabled them?
(See Coredumpdirectory, and check limitations imposed by your
operating system and shell).

> also tried to strace the Apache but this slowed the server down too
> much. And the error appears only on the live system with a very high
> load. Any ideas welcome here.

We recently (for 2.2.9) fixed a bug that fits that description:
http://issues.apache.org/bugzilla/show_bug.cgi?id=44402
But that's not relevant to prefork.

> At the same time we get broken TCP packets with a wrong window size 
> which looks like this:

Um, sounds like a problem in the network, below the level of apache.

> The box is used for dynamic webpages on PHP. Below are some system 
> information.

PHP is always a prime suspect for this kind of problem.
If you're using mod_php, make sure you really are running prefork,
as PHP+threads is a classic recipe for random segfaults.

> Sorry, this is not very much information but I'm still at the
> beginning of my Apache leraning curve.

Contradictory information is more of a problem.

-- 
Nick Kew

Application Development with Apache - the Apache Modules Book
http://www.apachetutor.org/

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