I have an Ubuntu server running three separate Rails (2.3.8) applications with Passenger, REE and Apache. Recently we started experiencing problems with ruby processes eating up memory and consuming entire cores on our server.

Here's what we're getting...

%CPU PID USER COMMAND
99.9 1717 nobody Rails: /var/www/api 
99.6 5542 nobody Rails: /var/www/api 
97.3 1223 nobody Rails: /var/www/api 
4.7 5537 nobody Passenger ApplicationSpawner: /var/www/api 
10.5 1801 nobody Rails: /var/www/api

We've also seen instances where there have been over 100 instances of Apache running. These applications have been running for a few months without an of these issues, but in the last day or so we've been noticing this. The site referenced here is a Rails application that is a RESTful API so it serves many requests every minute.

Any guidance on what we should be checking or looking out for would be appreciated.