Every so often my VPS server becomes unresponsive for no obvious reason. CPU usage is flat. No spike in traffic etc. When I run a top command on the machine (Centos) I can see that one of my sites has spawned loads of apache/httpd processes and is consuming the available RAM - yet there is virtually no traffic on the box.
I had a plugin installed that would backup the site every day (EZPZ backup: http://wordpress.org/extend/plugins/ezpz-one-click-backup/).
I had a nose through the source and I could see it added a number of WP Cron jobs to execute daily backups. I suspect this is the root cause of the issue but are there any good tools that help to monitor which php scripts are killing my machine when/if it happens again. (i.e is there a logging tool I can switch on to log slow or long loading php processes??).
I've since uninstalled the plugin and can see it has hooks to remove the WP Cron jobs it installed. Is there somewhere in the DB i can check WP Cron jobs to ensure they've definitely been removed?