Recently my server started to consume more RAM. Running processes became 500+. This never happened to me over the pass year. I have VPS / 2GB / Ubuntu / Virtualmin.
Apache has MaxClients 256 and default ServerLimit (256). The maximum number of user processes (ulimit -u) is 15891.
Error log file /var/log/virtualmin:
mod_fcgid: can't apply process slot for /home/seekdl/fcgi-bin/php5.fcgi
/var/log/apache2:
server reached MaxClients setting, consider raising the MaxClients setting
[Sat Oct 27 17:17:25 2012] [error] FastCGI process 11916 still did not exit, terminating forcefully
[Sat Oct 27 17:17:25 2012] [error] FastCGI process 12374 still did not exit, terminating forcefully
[Sat Oct 27 17:17:25 2012] [error] FastCGI process 11918 still did not exit, terminating forcefully