[Spread-users] Spread for HA rpc services

[Theo Schlossnagle]

You might want to take a look at ActiveMQ.

Actively developed, production ready (widely deployed) message broker  
providing (among other things) durable message queues with safe  
competing consumer semantics.  Very very fast with a lot of other  
features.

activemq.apache.org


On Aug 9, 2007, at 2:46 AM, Colin Meyer wrote:

> On Wed, Aug 08, 2007 at 05:26:36PM -0400, Daniel F. Savarese wrote:
>>
>> Since Colin's questions have already been answered, I just want to
>> touch on Colin's original description of wanting the "first available
>> server" to process a request.  The approaches described amount to
>> round-robin load balancing, which may or may not achieve the same
>> effect depending on your application.
>
> Agreed. Van's suggestion of hashing the input would would perhaps lead
> to a better distribution of jobs than round robin.
>
>> That's why I said there are
>> a number of different ways to go about it (exact answers are always
>> application-specific).  If the time to process a request is not a
>> constant, either because of heterogeneous hardware or because of the
>> nature of the processing, you run the risk of underusing or starving
>> your fast workers and piling up unprocessed requests for your slow
>> workers.
>
> In my case the hardware will be homogenous, and the jobs will  
> typically
> be well within an order of magnitude of each other (with the bulk  
> of them
> being nearly identical in difficulty).
>
> I suppose that one approach could be for a given server to remove  
> itself
> from the queue, while it was feeling overworked.
>
> -Colin.
>
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// Theo Schlossnagle
// Principal at OmniTI: http://omniti.com
// Esoteric Curio: http://www.lethargy.org/~jesus/