Ok every so often my website which runs on a ubuntu 9.04 vps seems to fall over as apache does not seem to respond.
a simple apache restart solves the issue but obviously it's not a good scenario having to manually restart the server every time this happens.
the site is a wordpress site with minimal traffic (max. 200 visitors a day) i've also got php running as an apache mod with APC caching setup.
i removed some processes which were running on the server like clamav which has reduced memory usage somewhat (server has half a gig of RAM).
users report seeing "out of memory" errors just before apache becomes responsive.
running a top command on the server now shows approx 50% memory usage.
the apache error logs not showing anything interesting either.
but running a top command shows me there are 4 unique instances of apache2 running - each consuming about 15% of memory. The cpu is at 0%
Can anyone explain why there are 4 individual apache processes running and how to manage these correctly?