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From Jeff Trawick <traw...@gmail.com>
Subject Re: [users@httpd] Runaway Apache Process
Date Wed, 27 Jan 2010 13:18:53 GMT
On Tue, Jan 26, 2010 at 8:28 PM, Dan Bunyard <danodemano@gmail.com> wrote:
> This has happened twice now and it's a little bit concerning to me. I have a
> Fedora 12 server with 5GB of RAM that I use to host a few small web sites of
> mine. As I mentioned, this happened once before. I tried to load one of my
> web sites today and it took FOREVER (as in the 10s of minutes) to load. I
> SSHed into the box and found the load average around 100 (dual core
> machine). Since this was the second time it had happened, I knew that it was
> Apache causing it. So I restarted the Apache service and everything returned
> to normal. A look in the error_log showed this error:
>
> server reached MaxClients setting, consider raising the MaxClients setting
>
> I suspect that this is the reason that Apache was eating up all my system
> resources but I don't have any idea how to fix it.

This means that you have 100 active client connections, and that's the
limit of your configuration (MaxClients=100).

I didn't catch whether or not you had high CPU utilization.

I didn't catch whether or not you had a high number of requests being
processed during this time.

High CPU utilization, relatively low number of requests:

I'd guess that some application code running inside Apache encounters
an unexpected situation that results in loops or other extremely high
CPU that prevents the request from being completed within a reasonable
period of time (or ever).  The fact that you could log in after a
while suggests that some of this faulty request processing does
eventually finish.

High CPU utilization, relatively high number of requests:

Your server is just being overwhelmed -- application request
processing requires noticable CPU, and the box can't handle large
numbers of concurrent requests.  Likely some application-level
optimization will help.


If you pick an httpd child process and get backtraces of it at
intervals with gdb to see where it is spending its time, that might
provide valuable clues.

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