[rabbitmq-discuss] Flow Control in RabbitMQ 1.5.3

Wed Apr 1 18:53:35 BST 2009

Chris,

Chris Pettitt wrote:
> The difference in my producer is that it uses persistence.

Ah, I thought that might be the case. There is a known performance 
limitation in the persister: In some scenarios RabbitMQ will end up 
spending most of its time writing new snapshots. That's because the time 
it takes to write a snapshot is proportional to the amount of persisted 
data, and snapshots are written every 500 entries (i.e. publishes, 
deliveries, acks) by default. Writing new snapshots is also very memory 
intensive.

Work is underway to fix this, but it's going to take some time.

> Is persistent messaging compatible/supported with producer flow control?

Yes, but because of the stress caused by the persister, the limits have 
to be set very low.

Matthias.