[zeromq-dev] Distributed Q with **lots** of consumers

Sean Donovan sdonovan_uk at yahoo.com
Wed Nov 14 06:09:34 CET 2012


It is possible to estimate, accurately in fact.  We can record execution times from previous runs.  However, for many million of tasks that is a lot of overhead. However, I think there is a simpler approach.  Instead, I think I can batch messages as "very fast execution" (where tasks take 3ms, the minimum) and "everything else".  So, the fast tasks I'd batch (e.g. of 100) -- then send everything else individually.  Determining which messages/tasks are very fast is relatively trivial -- determining everything else is laborious.

Trying (a) to optimize minimum idle time by (b) ensuring that the messaging adds as little overhead as possible and (c) taking into account there could be hundreds of cores (either Windows|Linux boxes with 64+cores) or the newer generation SPARC T-series CPUs.  The other factor is the task execution time.  Each task is actually a pricing of a derivative trade.  Depending on the trade type/configuration, there are many complex pricing-models involved.  Optimizing a given pricing-model is a project (well, challenge) in it's own right.

Many thanks,

Sean


________________________________
 From: Andrew Hume <andrew at research.att.com>
To: Sean Donovan <sdonovan_uk at yahoo.com>; ZeroMQ development list <zeromq-dev at lists.zeromq.org> 
Sent: Monday, November 12, 2012 10:08 PM
Subject: Re: [zeromq-dev] Distributed Q with **lots** of consumers
 

is it possible to estimate the runtime for an item?

and what is the metric you are trying to optimise?
is it average latency? or total throughput? or minimal idle time?


On Nov 12, 2012, at 3:58 PM, Sean Donovan wrote:

Any suggestions for implementing the following in ZMQ?
>
>
>Imagine a single Q containing millions of entries, which is constantly being added to.  This Q would be fully persistent, probably not managed by ZMQ, and run in it's own process.
>
>
>We would like N workers.  Those workers need to start/stop ad-hoc, and reconnect to the Q host process.  Each worker would take a single item from the Q, process, acknowledge completion, then repeat (to request another item).  Processing time for each task is 3ms+ (occasionally minutes).
>
>
>Because of the variance in compute time it is important that the workers don't pre-fetch/cache tasks.  As an optimization, we'll add a heuristic so we can batch short-running tasks together (but, we'd like the control -- a load-balancing algorithm wouldn't know how to route efficiently, unless it could take hints).
>
>
>Need a pattern that would allow us to scale to 100s of workers.  
>
>
>MANY THANKS!
>
>Sean Donovan_______________________________________________
>zeromq-dev mailing list
>zeromq-dev at lists.zeromq.org
>http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>


-----------------------
Andrew Hume
623-551-2845 (VO and best)
973-236-2014 (NJ)
andrew at research.att.com
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