[Web4lib] mediawiki and excessive CPU usage

[Cary Gordon]

FYI, strace is not usually installed in RedHat Linux flavors and their
relatives (Fedora, CentOS). On RHEL, you can run "up2date strace" or, on
Fedora and CentOS, "yum install strace". Everyone else can download it from
SourceForge and build it from source. 

Cary Gordon
The Cherry Hill Company
http://www.chillco.com

-----Original Message-----
From: web4lib-bounces at webjunction.org
[mailto:web4lib-bounces at webjunction.org] On Behalf Of Michael McDonnell
Sent: Tuesday, July 10, 2007 11:30 AM
To: Ken Irwin
Cc: web4lib
Subject: Re: [Web4lib] mediawiki and excessive CPU usage

Ken Irwin wrote:
> Hi folks,
>
> We've got a wiki running on our library website (using MediaWiki
> 1.6.8) and have noticed that since installing it our CPU usage is 
> almost always right up at 99% of capacity. About 100 distinct 
> processes related to the wiki run about 2000 times every minute. It 
> may be that a high-traffic wiki needs all this legwork to keep itself 
> up-to-date and functioning well, but this is a super low-traffic wiki.
> Does anyone know if it's possible to get wiki to chill out a bit? 
> ($cpuQualudes = "yes";)
>
> We're thinking of installing additional wikis on the same machine for 
> different purposes, and we'd like to not fry its little brain. Any 
> advice?
Hi Ken,

This may be a misconfiguration or a bug.  What platform are you running
mediawiki on?  Apache on Linux?  What version of PHP?  How much RAM does
your server have?

Do you see any logfile activity that corresponds with this activity?  
That is, are there access or error logs being generated in large volumes?
You can change what apache is logging by changing the "LogLevel"
configuration line (typically in httpd.conf).  Change it from "notice" to
"info" or "debug" and see if that provides any relevant information.

Under linux you can also take a peak at what those crazy processes are doing
with the  "strace" command (under Solaris 10 you could use dtrace). e.g.
strace -p <pid> where <pid> is the ID of one of the crazy processes.

--
Michael McDonnell
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