Know your ulimits.

When running Apache HTTP Server 2.2 and / or JBoss Enterprise Application Platform (EAP) 6 on Red Hat Enterprise Linux (RHEL) 6 with a high number of concurrent connections, the user resource limits may need to be changed.

This post highlights two scenarios where the user resource limits may need to be changed: the maximum number of user processes is too low, the maximum number of open files is too low.