[Users] apache2 stall in CLOSE_WAIT state

[Yoann Moulin]

Hi,

I have a VE in production for a couple of months. HN and VE are running 
Ubuntu Dapper 6.06.2 LTS

> vz01:~$ uname -a
> Linux vz01 2.6.18-028stab053 #1 SMP Tue May 27 15:40:07 CEST 2008 x86_64 GNU/Linux
> vz01:~$ vzctl --version
> vzctl version 3.0.22

This VE is only used for http(s) services. Everything have worked well 
until this week end where we got apache process stalled on CLOSE_WAIT 
state and no more process are available to deliver pages

We get this in logs :

> server reached MaxClients setting, consider raising the MaxClients setting

If I set MaxClients to a higher value, that is just delaying the moment 
where apache fall in a stalled state.

I gave a look into user beancounter but no hard limit or barrier limit 
was reached when it occurred.

since it's a production server I can't "play" too much with. I don't 
know if it's a fully openvz related but I restarted the server on a 
physical blade and the problem has been fixed.

For now, the server is running on a physical blade, but I can reboot it 
as a VE server to do some test.

The server is behind a reverse proxy cluster (lighthttp) but nothing has 
been change on those servers for a couple of weeks.

Note : In our architecture, each physical or virtual server is format 
after each reboot and populated with a clear boot image. After that, we 
are using cfengine to apply the right configuration function of the name 
of the server. I can boot a server on a physical or a virtual server 
with exactly the same configuration even if specific openvz 
configuration (such as not start ntp server for example).

> ii  apache2                2.0.55-4ubuntu2.3            next generation, scalable, extendable web se
> ii  apache2-common         2.0.55-4ubuntu2.3            next generation, scalable, extendable web se
> ii  apache2-mpm-prefork    2.0.55-4ubuntu2.3            traditional model for Apache2
> ii  apache2-utils          2.0.55-4ubuntu2.3            utility programs for webservers
> ii  libapache2-mod-php5    5.1.2-1ubuntu3.10            server-side, HTML-embedded scripting languag
> ii  libc6                  2.3.6-0ubuntu20.5            GNU C Library: Shared libraries and Timezone
> ii  php5-cgi               5.1.2-1ubuntu3.10            server-side, HTML-embedded scripting languag
> ii  php5-common            5.1.2-1ubuntu3.10            Common files for packages built from the php
> ii  php5-mcrypt            5.1.2-1                      MCrypt module for php5
> ii  php5-mysql             5.1.2-1ubuntu3.10            MySQL module for php5
> ii  php5-mysqli            5.1.2-1ubuntu3.10            MySQL Improved module for php5

Thanks for you help.

Regards,

Yoann