[rabbitmq-discuss] Ready, Unacked and Total messages of Queues

[Michael Klishin]

On 15 April 2014 at 11:37:39, Juno Chan (juno at algorithmictradinggroup.com) wrote:
> > thanks very much. So, for the queues having high values in ready&  
> total # of messages(even go up to 300K messages), rabbit MQ performance  
> won't get affected?
> only those queues having high values in unacked and total would  
> harm the rabbitMQ performance, is that correct?

Unacknowledged messages are still kept around by RabbitMQ until they are acknowledged
or rejected, so it’s the total number of messages that really  matters.

> BTW, for 2 applications subscribing to the same subscribe channel,  
> 2 separate queues are created, if for some reasons, one of them  
> has problems and cause the queue stuck (e.g. high # unack messages)  
> will another queue being affected?

A single queue can only use a single CPU core. The number of messages in the longest
matter a lot less compared to how much disk I/O RabbitMQ has to do, either due to
memory pressure or a high rate of messages published as persistent and routed to
durable queues.

Avoid overloaded queues as much as possible. See also

http://www.rabbitmq.com/blog/2014/01/23/preventing-unbounded-buffers-with-rabbitmq/
http://www.rabbitmq.com/blog/2014/04/10/consumer-bias-in-rabbitmq-3-3/
http://www.rabbitmq.com/blog/2014/04/14/finding-bottlenecks-with-rabbitmq-3-3/
--  
MK  

Software Engineer, Pivotal/RabbitMQ