I've mentioned before that I've been dealing with unexplained server spikes for weeks now, maybe months :-O They're totally sporadic and I can't find a pattern: one request the server load will be 0.6, and the next request jumps up to 150!

Today I noticed that there were two httpd requests with high CPU usage that had been running for a long time. I tracked the PID of one of them in the access log back to Google Imagebot, but 2 hours prior! So I guess it opened but then never closed? I'm not sure.

I tried turning off KeepAlive in the thoughts that it would force a new PID for each request instead of having one open forever like that, but then my server load kept spiking over and over! So that was no good.

Then I enabled RLimitMEM, and I haven't had a major spike since! The highest I've seen is 15... high, but nowhere near the 150 I'd been seeing before!

WHM/cPanel has a recommendation of a value of 796M for the RLimitMEM value, but I don't know if that's generic or based on some calculation on my server.

Any suggestions on calculating a "proper" value?