Bill Marrs wrote: > But... recently, something happened, and things have changed. After > some random amount of time (1 to 40 minutes or so, under load), the > parent httpd suddenly loses about 7-10mb of share between it and any new > child it spawns.
One possible reason is that a perl memory structure in there might be changing. Perl is able to grow variables dynamically by allocating memory in buckets, and it tends to be greedy when grabbing more. You might trigger another large allocation by something as simple as implicitly converting a string to a number, or adding one element to an array. Over time, I always see the parent process lose some shared memory. My advice is to base your tuning not on the way it looks right after you start it, but on the way it looks after serving pages for a few hours. Yes, you will underutilize the box just after a restart, but you will also avoid overloading it when things get going. I also recommend restarting your server every 24 hours, to reset things. One more piece of advice: I find it easier to tune memory control with a single parameter. Setting up a maximum size and a minumum shared size is not as effective as setting up a maximum *UNSHARED* size. After all, it's the amount of real memory being used by each child that you care about, right? Apache::SizeLimit has this now, and it would be easy to add to GTopLimit (it's just $SIZE - $SHARED). Doing it this way helps avoid unnecessary process turnover. - Perrin
