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From "Boyle Owen" <Owen.Bo...@swx.com>
Subject RE: [users@httpd] Troubleshooting Tips?
Date Tue, 06 Feb 2007 08:06:08 GMT
> -----Original Message-----
> From: Evan Klitzke [mailto:eklitzke.lists@gmail.com] 
> Sent: Tuesday, February 06, 2007 1:21 AM
> To: users@httpd.apache.org
> Subject: [users@httpd] Troubleshooting Tips?
> 
> Hi everyone,
> 
> I am a junior sysadmin (well, intern actually) at a company using
> Apache. Right now I am tasked with migrating one of our servers to a
> newer machine, and this involved doing more work with Apache 
> than I have
> done previously. I encountered a problem where turning on 
> mod_perl would
> cause Apache to run _really_ slowly (as in taking a minute to return a
> small plain HTML page). In this case, I was sort of at a loss 
> on how to
> figure out what was causing the problem. The access and error logs
> in /var/log/apache2 weren't showing anything helpful. The man page
> indicated that I might be able to get some debugging output 
> using the -X
> option and starting apache at the command line, but I didn't get any
> output (probably apache didn't consider anything that was going on
> seriously amiss). Since this is something that will come up in the
> future again I'm sure, I'm wondering: what is the best way to
> troubleshoot Apache problems? Is there a way to turn on really verbose
> logging, or to otherwise figure out what the heck is going on when
> Apache spends 2-3 minutes just starting itself? 

I'm as bit confused - is apache slow in starting, or serving once
started, or both?

General tips: slow operation can be caused by using hostnames instead of
IPs in VirtualHost tags etc. This causes apache to rely on DNS at
startup (http://httpd.apache.org/docs/2.2/dns-caveats.html).

Other issues are network latency (eg, content on NFS) and avoiding
sendfile
(http://httpd.apache.org/docs/2.2/mod/core.html#enablesendfile).

> This is especially
> pertinent when Apache isn't actually encountering errors, it is just
> running an order of magnitude more slowly than it ought to 
> be. I realize
> there's strace, but using it on something as big and complex as Apache
> is somewhat daunting.

Maybe - but it might be worth it.. start httpd with the -X option under
strace/truss, eg:

	strace httpd -X -f /path/to/config

and sew where it is "waiting"...

Rgds,
Owen Boyle
Disclaimer: Any disclaimer attached to this message may be ignored. 


> 
> Thanks a lot!
> Evan Klitzke
> 
> 
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