[Phpwm] Problems with live Silverstripe website (httpd spawing proceses, high CPU)

[Pete Graham]

Hi everybody,

I have a live SilverStripe site I've inherited that I'm experiencing
major problems with. After the site has been running for a while it
starts spawning multiple httpd processes, some taking up huge
percentages of the CPU (these can be seen using top). The site
progressively become more and more unresponsive returning 500 errors
for requests.

Has anyone experienced similar behaviour on a server/site? I'm trying
to determine if the problem is with the Apache setup or if it's been
caused by the PHP (Silverstripe) application. At first I thought this
was most likely to be an server misconfiguration, but the apache setup
seems ok. Could some dodgy logic in the PHP cause this behaviour, is
it even possible to make Apache (mis)behave like this using PHP? It
happens inconsistently which makes trying to fix the problem a joy!

The site has low to medium traffic and is on fairly hefty dedicated
server so should be able to handle the load easily. I've been running
Apache Bench on the live server and profiling the code (on my dev
server) however this hasn't shed any light on what's going wrong yet.
Any assistance would be greatly appreciated, I'm starting to go
slightly mad.

Pete

ps. Apologies to anyone also on the PHP New Zealand mailing list
(unlikely) that recieved a similar email, apparently it's where the
Silverstripe devs hangout, but I think their all in bed.