Increase file descriptor for RabbitMQ

(1) Update system's ulimit.

$sudo pico /etc/security/limits.d/mylimits.conf

* soft nofile 300000
* hard nofile 300000
* soft nproc 300000
* hard nproc 300000

(2) Update rabbitMQ config

$sudo pico /etc/default/rabbitmq-server

ulimit -n 300000

(3) Restart rabbitMQ

$sudo service rabbitmq-server restart