Mind the limits !

Running load simulator programs from linux might lead you to a limit ! This limit is often met through messages like :

Too many opened files

or in Erlang a more criptic message for the newbie :

{{badmatch,{error,emfile}},[{gen_tcp....

It means you've bump on the hard limit of opened files by processes.
Changing the values in /etc/limits.conf or /etc/security/limits.conf will allow you to raise those limits.
Don't forget to close all your shell sessions to allow the system to effectively raise the limit !