[rabbitmq-discuss] 1 Fanout Exchange, 2 queues, 1 slow, 1 fast

Tue May 8 11:47:05 BST 2012

Hi Kenneth,

On 07/05/12 20:10, Kenneth Loafman wrote:
> I've got a fanout exchange running two queues.  One queue is responding
> very quickly like normal, the other is intermittent.  What would cause
> this?  The fast queue has 3 consumers, the slow queue has 64 consumers.
>  Is there a limit to how many consumers can be attached to a queue?

If you say the queue is responding intermittently, what do you mean
exactly? Are you measuring latency between publish and deliver, or
something else?

The broker does not impose a fixed limit on the number of subscribers to
a queue, but the server capacity may be a limit.

It is possible that the problem is caused by some behaviour of the
clients, or a difference in pre-fetch count. Do you get more comparable
performance if you set the pre-fetch count to 3 on the "intermittent" queue?

Depending on what you are measuring you may wish to enable the firehose
tracer for debugging:

http://www.rabbitmq.com/firehose.html

-Emile