[rabbitmq-discuss] direct queue throughput

Sun Aug 30 21:13:26 BST 2009

On Aug 28, 2009, at 6:01 PM, Matthew Sackman wrote:

> On Fri, Aug 28, 2009 at 05:38:58PM -0500, Chuck Remes wrote:
>> I don't have an answer for you but I do have a few things to point  
>> out.
>>
>> 1. RabbitMQ is written in Erlang. I am pretty sure the latest stable
>> releases are still a single-threaded process (though internally the
>> application uses hundreds or thousands of "green" threads). Therefore
>> you won't get much throughput increase by running on a larger multi-
>> core box.
>
> Erlang has supported SMP for several releases, I believe first gaining
> support about 4 years ago. Initially, yes, we found that very early
> versions of Rabbit ran slower with the SMP support turned on that off.
> However, Erlang's support for SMP has improved substantially over the
> years and Rabbit benefits substantially from Erlang's SMP support.

I don't disbelieve you but in my testing I have never seen a rabbit  
process go above 100%. This is using Erlang 13B and the "generic" unix  
rabbitmq 1.5.5 under OSX. Perhaps the defaults disable SMP?

cr