Apache 2.2.11 Segfaults when using Memcache PHP-API(2.2.4) and Memcached (1.2.6) on Linux 2.6.27.9

[Wayne]

Hi folks,

first of an overview about the software I'm currently using on the
webserver:
- Apache 2.2.11
- PHP 5.2.8
- Memcache 1.2.6 PHP-API
- Memcached-Daemon 2.2.4
- Libevent 1.4.5-stable

Since I've upgraded the Kernel of the Webserver from version 2.6.26.8
to version 2.6.27.9 the Apache Webserver on the machine started to
Segfault:

[Thu Dec 18 13:38:09 2008] [notice] child pid 6586 exit signal
Segmentation fault (11)
[Thu Dec 18 13:38:09 2008] [notice] child pid 6587 exit signal
Segmentation fault (11)
[Thu Dec 18 13:38:09 2008] [notice] child pid 6588 exit signal
Segmentation fault (11)
[Thu Dec 18 13:38:09 2008] [notice] child pid 6590 exit signal
Segmentation fault (11)

Well, bad news so far. I've then activated Core Dumps within Apache
and started to generate Requests
with Apache Bench and checked the Core Dump (gdb /usr/local/apache2/
bin/httpd /tmp/core). In the CoreDump i can see the following:

Reading symbols from /usr/local/lib/php/extensions/no-debug-non-
zts-20060613/memcache.so...done.
Loaded symbols for /usr/local/lib/php/extensions/no-debug-non-
zts-20060613/memcache.so
Failed to read a valid object file image from memory.

As soon as I deactivate "extension=memcache.so" from the PHP php.ini
file, Apache is running without any
Problems nor Segfaults. In the next steps I've done the following

- Recompiled the Memcache PHP-API 2.2.4
- Switched the Memcache PHP-API from 2.2.4 to 3.0.2beta
- Reinstalled Memcached 1.2.6
- Updated libevent from 1.4.5stable to 1.4.8stable

Without any luck :-( With Linux Kernel 2.6.26.8 beneath everything is
just working fine. Do you have an
idea? Please, tell me any information you need for helping me
debugging this issue, i really want to
solve this :-)

thank you for all your help,
Wayne

[cidcampeador]

Got almost the same errors here.

We recently upgraded to Ubuntu 8.10, which brings Kernel 2.6.27.

I've debugged this problem till see it's somewhat related to getting
objects from a remote memcache server. It works fine sometimes, and
then the Apache process crash.

Tested on:
Apache 2.2.9 and 2.2.11
PHp 5.2.6 and 5.2.8
php5-Memcache 3.0.3 and 3.0.2

I've got some other servers running prior kernel and PHP-memcache
versions with the same PHP code and run perfectly fine.

I have other network problems with Kernel 2.6.27. Masquerading
suddenly stopped working too.

Kitai

[wer...@aloah-from-hell.de]

Hi,

I've tracked down the Source of the Problem, see
https://issues.apache.org/bugzilla/show_bug.cgi?id=46501

Ciao,
Werner Detter

[cidcampeador]

Did changing that value solved the problem for you?

Cause i cannot see that tunable spot in the ubuntu kernel we're using.

Kitai


On 16 ene, 13:27, "wer...@aloah-from-hell.de" <wer...@aloah-from-
hell.de> wrote:
> Hi,
>
> I've tracked down the Source of the Problem, seehttps://issues.apache.org/bugzilla/show_bug.cgi?id=46501

[wer...@aloah-from-hell.de]

Hi,

yes, setting 'echo 1024 > /proc/sys/fs/epoll/max_user_instances'
where 1024 ist something
larger than MaxClients fixed this issue for me (also verified on
Kernel 2.6.28.1).

Ciao,
Werner