In the last weeks, it happened several times to me that my vserver (Debian Lenny) was out of RAM (500M) and therefore wasn't able to run apache anymore. When looking at the processes with
top, I saw that there were many open
munin-cron processes that consumed most of the memory.
My guess would be that sometimes Apache temporarily needs more memory, which prevents
munin-cron from running. And if munin-cron isn't able to stop itself, it would fill the memory until nothing is left.
I don't know whether this guess is true, but could maybe someone know what the problem is and how to prevent it? If necessary I'll remove munin, but I'd prefer to keep it running.