[rabbitmq-discuss] Increasing the file descriptors limit

[Tim Watson]

Hi 

On 17 Jan 2013, at 12:26, Jean Paul Galea wrote:
> We're trying to increase the file descriptors limits for RabbitMQ to no avail. Here's what we did;
> 
> ~# # check the current nofile value
> ~# su rabbitmq -s /bin/sh -c 'ulimit -n'
> 1024
> 
> ~# # set soft,hard nofile limit for 'rabbitmq' user to 102400
> ~# cat >> /etc/security/limits.conf << "EOF"
> rabbitmq	-	nofile	102400
> EOF
> 

Don't you need to change /etc/sysctl.conf as well?

> ~# # pam_limits.so is required for limits.conf to take affect
> ~# cat >> /etc/pam.d/common-session << "EOF"
> session	required	pam_limits.so
> EOF
> 
> ~# # verifies new setting
> ~# su rabbitmq -s /bin/sh -c 'ulimit -n'
> 102400
> 

Hmn, does `sysctl fs.file-max` return the same?

> However, RabbitMQ fails to start up with this limit. We have tried restarting the RabbitMQ service and also a system reboot.
> 
> ~# rabbitmqctl status
> {file_descriptors,
> [{total_limit,924},{total_used,3},{sockets_limit,829},{sockets_used,1}]},
> 
> ~# rabbitmqctl eval 'proplists:get_value(max_fds, erlang:system_info(check_io)).'
> 1024
> ...done.

Was erlang compiled with epoll support enabled? Erlang will fall back on 'select' if it can't find/use epoll or if epoll is not enabled during compilation, and that will leave you with max 1024 fd limit, regardless of what the OS will allow.