[rabbitmq-discuss] Consistent Hash Exchange Type

Sun Sep 25 07:35:15 BST 2011

Hi Matthew,

Sounds great, thanks for doing this! I hope I get a chance to try it out.

On Sat, Sep 24, 2011 at 11:03 PM, Matthew Sackman <matthew at rabbitmq.com> wrote:
> Hi,
>
> I've just written a consistent-hash exchange type plugin. See
> http://hg.rabbitmq.com/rabbitmq-consistent-hash-exchange/file/default/README.md
> for the full README.
>
> Currently, I've not done a .ez release so you'll need to compile
> yourselves, but I'll get around to the .ez early next week, I hope.
>
> Essentially, this plugin allows you to use an exchange to load-balance
> messages between queues in such a way that the loss or addition of
> queues does not cause substantial changes to the bucket selected by a
> hash.
>
> Normally we strongly suggest that you should have multiple consumers
> hanging off a single queue and rely on the queue to do round-robin
> between the consumers. However, in some cases, the performance of a
> single queue is not sufficient and, as a queue is single threaded,
> routing messages to multiple queues, especially on different machines
> within the same cluster, can achieve much higher overall performance.
> Without something like a consistent-hash exchange type, engineering such
> a distribution of messages is difficult. There are other applications
> too for such an exchange type.
>
> As ever, feedback welcome. Note that this has received not a great deal
> of testing so far - it's rather hot off the press - and whilst it works
> for me, that's not to say there aren't bugs in it!
>
> http://hg.rabbitmq.com/rabbitmq-consistent-hash-exchange
>
>
> Matthew
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