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From Damian Meyer <>
Subject Re: [users@httpd] Timeouts / responsiveness issues with Apache
Date Sat, 17 Jan 2004 04:47:53 GMT
Hi Matthew,

Yes, further experimentation/investigation is leading me to think the 
same things.  PHP module is big, but its also our bread and butter (and 
many of our clients).  What I need to start figuring out is why memory 
increases, or the right settings to keep that under control.

Nothing in /var/log/messages of note.

Kind regards
Damian. wrote:

>This behavior suggests a memory problem. You should never have to "cycle"
>your servers. If the memory usage climbs and climbs, your problem is
>somewhere else. Do you have too many modules loading as DSO's? Perhaps one
>of these is being used more than you anticipated. If you are running ssl,
>have you tried compiling it in statically? The PHP module is pretty hefty
>and ( in a couple of my cases at least ) caused each of the http threads
>to rise from less than a meg each to 4 megs. This quadrupled my memory
>usage and required some module rearrangement. During one of these time out
>periods, do you have system problems ( error entries in /var/log/messages
>)? Inquiring minds want to know! :)
>-Matthew Shannon
>>Damian Meyer wrote:
>>>We have recently migrated from several individual Apache 1.3.x servers
>>>running around 1000 virtual sites each to a server farm with multiple
>>>servers (Apache/1.3.29) all capable of running all of the sites (about
>>>4000 in total).  The server farm is behind a load balancer running
>>>ldirectord from the LVS project.
>>>The problem we are having is that every so often one of the web servers
>>>seems to go offline and either become very sluggish with responses or
>>>even times-out.  If it failed totally, ldirectord would notice and map
>>>it out, but it doesn't (usually).  After a few minutes of bad
>>>performance, it usually comes good, but it happens frequently enough to
>>>one or more of the web servers that it's causes noticeable glitches to
>>>our clients.
>>>Also, and it may or may not be related, occasionally Apache dies totally
>>>(ie no live processes) and requires starting again.
>>>Each server has 2GB of RAM.  Websites are a mix of flat HTML through to
>>>complicated PHP sites using MySQL connections (we've checked the
>>>database, it doesn't look like this is the problem.)
>>>Does anyone have any idea what could be at issue here?  Does anyone have
>>>any experience with this sort of large-ish server farm to give us any
>>>feedback on configuration settings or other tuning parameters?  Any
>>>decent tuning documents on the web that take into account this type of
>>>Kind regards
>>>Damian Meyer
>>Since you are using PHP [with many sites], I would consider lowering
>>"MaxRequestsPerChild" so that child processes die after a reasonable
>>amount of requests.
>>I would consider trying regular restarts of apache via cron.  Since you
>>have load balanced servers, you should not be too concerned with it
>>failing to restart on one server.  I like Apache and all, but I have had
>>issues with process "build-up" on heavily used instances.
>>Aaron W Morris <> (decep)

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