[rabbitmq-discuss] Changing file descriptor limit wihtout restart?

Simon MacMullen simon at rabbitmq.com
Mon Jul 7 10:35:49 BST 2014

On 06/07/2014 12:03AM, Jakov Sosic wrote:
> which brings us back to original question, is there a way to increase
> the descriptor limit for running RabbitMQ server? Is there a way for
> ERLang process to figure out limits have changed?

It's not Erlang, it's RabbitMQ. The problem is that the file handle 
cache (the component which manages file descriptors inside the broker) 
only checks the limit at startup.

But you can tell it the limit has changed with something like:

$ rabbitmqctl eval 'file_handle_cache:set_limit(4096).'


This number is not validated; it's taken entirely on trust. If you tell 
the FHC that it has a larger limit than the one the OS will enforce, you 
can run out of file descriptors and crash the server.

Cheers, Simon

Simon MacMullen
RabbitMQ, Pivotal

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