Zombie Proccesses at 250+ reqs/min. High load php...

Hey folks,

A site I run has begun hitting over 250 reqs/minute which is great :) What's
not so great is that the PHP stuff I put together can't seem to handle the
load. I'm looking for others sense of what may be going on. It is exciting
to run a high traffic site using PHP, but we can't do so if PHP falls down.

I'm most interested in ways in which PHP might create zombies and/or exit
uncleanly. In a high load situation this can be deadly.

Running PHP4.0.0 as a CGI, using something similar to the optimized version
of php.ini.
Sessions are enabled and used. Auto Start == true
The general outline of a page load is a call to a script which includes()
3-4 files,
creates a new instance of a larger class (2,000 lines or so),
calls the appropriate methods on the class,
exit those methods, opens a logfile and writes some auditing data.


A couple of questions include:
What's the overhead on creating a large class? We can certainly avoid doing
so.
Often times the script sends out a redirect. Any chance this blows things
out of the water?
Would opening and closing a log file at that rate lead to problems?
Anyone else have high load problems with PHP4? We might be able to backport
and do our own sessions.
Do we need to make sure we call exit? Release resources?
The script tends to execute in something like .3 seconds and is not
long-running from that point of view.

We are already planning on moving to mod_php.
What concerns me is the specter that PHP is leaking resources or generating
zombies which will not disappear no matter how much hardware we throw at the
problem. Tips and tricks for very high load programming (going onto a
million requests/day) would be appreciated. Gotchas especially within the
language. We've got a ton of global statements, does that matter? You
wouldn't think so but who knows? We are certainly going to throw hardware at
the problem.

Basically, I'd love to have PHP scale along for the ride! It's a great
package.

August Zajonc
Please CC me if possible as my free access net connectivity is limited and
it is hard to track the list directly :)








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