[rabbitmq-discuss] rabbitmq memory usage

Simon MacMullen simon at rabbitmq.com
Thu Jun 6 15:38:39 BST 2013

On 06/06/13 15:03, Ceri Storey wrote:
> I'm sure that one of the Rabbit team themselves can shed a bit more
> light on this, but AIUI RabbitMQ uses ETS in-memory tables to index the
> queues,

Minor correction / clarification: the in-memory cost is per-message in 
the message store, not queues per se. So a message which ends up in lots 
of queues incurs the cost once.

> so with some back of the envelope arithmetic your rabbit is
> using approximately 175bytes per message. So on the face of it, that
> might look a bit odd, but doesn't seem unreasonable.

That cost is about right.

Also, note that the OP did not specify the version of RabbitMQ used, but 
it looks like 2.x. 3.x will helpfully separate out the memory used by 
the message store index. See http://www.rabbitmq.com/memory-use.html

The rabbitmq-toke plugin offers an alternative message store index which 
does not have a per-message cost. Setting it up is a bit fiddly though, 
and it's less well tested.

Cheers, Simon

Simon MacMullen
RabbitMQ, Pivotal

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