Common causes for Apache exiting with SIGSEGV?

Hi,

I have a website that's built with PHP and MySQL and it works just
fine, most of the time. However, when the load gets higher (say 3
hits per second), Apache starts to exit with SIGSEGV on almost every
request.

Are there any typical areas to look at to solve these kinds of
problem?

Thanks,

Morten

On 17 Apr 2005 05:21:16 -0700, morphex@gmail.com (Morten W. Petersen) wrote:

>I have a website that's built with PHP and MySQL and it works just
>fine, most of the time. However, when the load gets higher (say 3
>hits per second), Apache starts to exit with SIGSEGV on almost every
>request.
>
>Are there any typical areas to look at to solve these kinds of
>problem?

Can you tie the date/time of the exit together with the logs to narrow down
the pages that might be triggering the failure?

The PHP bug reporting page has this information on how to get a backtrace out
so you can find out exactly where it happened:

http://bugs.php.net/bugs-generating-backtrace.php

--
Andy Hassall / <andy@andyh.co.uk> / <http://www.andyh.co.uk>
<http://www.andyhsoftware.co.uk/space> Space: disk usage analysis tool

One quick glance of an experienced eye allowed to understand the blurred
and almost unreadable Morten W. Petersen's handwriting:

> Hi,
>
> I have a website that's built with PHP and MySQL and it works just
> fine, most of the time. However, when the load gets higher (say 3
> hits per second), Apache starts to exit with SIGSEGV on almost every
> request.

Hmmm... Just brainstorming, but do you use permanent connections
(*_pconnect() functions)? If so, check if the maximal allowed number of
Apache's child processes (it's a conf setting) exceeds the database's
max connections limit. If so, then this *might* well be your problem.
Also, check www.php.net on permanent connections (search "pconnect",
you'll find it there somewhere).

But - as I said - just brainstorming here...

Cheers
Mike

> Hmmm... Just brainstorming, but do you use permanent connections
> (*_pconnect() functions)? If so, check if the maximal allowed number of
> Apache's child processes (it's a conf setting) exceeds the database's
> max connections limit. If so, then this *might* well be your problem.
> Also, check www.php.net on permanent connections (search "pconnect",
> you'll find it there somewhere).
>
> But - as I said - just brainstorming here...

I believe the maximum number of connections to the MySQL database is
500, so that's not the issue. Could it be that Apache is running with
mpm_worker?

I think running it with prefork would be worth a shot, and if that
doesn't help, I'll try the procedure with gdb mentioned above.

Thanks,

Morten