We're running into a weird problem with our 2.3.2 install (actually, it's been an issue since we migrated to 2.0). I posted the details over on the General forum the other day, but then noticed Hardware/Performance, which is probably more applicable.
Rather than repost the whole thing, I'll just put the link to it here:
Quick summary: Some activity/event (I suspect quizzes) are causing stale database connections to accumlate between our Moodle web & db servers. The problem eventually builds to a point where the web server becomes non-responsive & requires an httpd restart.
Persistent db connections in PHP have been disabled, so we're not sure where the problem is coming from. Any help would be appreciated - more details are at the link above.