Balancing between load and site stability (500 errors) with max-procs in lighttpd

I have a rather large dynamic site running off a single lighttpd powered box (1.3 million page views per day).

But Im frequently getting random 500 errors on the site, which sometimes go away within a second or 2... or sometimes not going away until lighttpd service is restarted.

If I set the max-procs to something low... like 2-4..... the server load is relatively low.... about 2-3 (at least for the hardware and the level of traffic), yet Im getting VERY frequent 500 errors. If I raise the procs to like 6-8, the server load doubles.... but I get less of these hiccups.

I currently settled at 6... which works out okay, but I still get quite a few of these intermittent 500 errors... with a non-recovering one every few days that requires a lighttpd restart.

What can I do?

The site is php/mysql powered.

From serverfault Yegor

• This problem may be the one that they have documented on the lighty site.

  Why is my PHP application returning an error 500 from time to time?

  Yegor : Interesting. Will try this out.
  From sybreon