[rabbitmq-discuss] Throttling when Fast Producer, Slow Consumer

Wed Mar 14 13:58:25 GMT 2012

Hi Paul,

On 14/03/12 13:38, Bell, Paul M. wrote:
> A couple of questions about your prior e-mail where you said "queues
> may get very long and need to spill over to disk..."
> 
> 1. Am I right to think that this "spill over" happens for non-durable
> exchanges and queues?

Exchanges store no message state.
The broker may decide to move message from RAM to disk even if the queue
was declared non-durable.

> 2. Is there a way to govern when that spill over occurs, e.g., when
> queue gets to a certain size, or is this auto-magically handled by
> Rabbit?

This happens automatically and depends on how fast the queue is moving
and the amount of free RAM, among others. You have some indirect control
in the shape of the vm_memory_high_watermark configuration parameter:

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

-Emile