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Date: Fri, 11 Nov 2005 15:40:05 +0100 (CET)
From: "dave irving (JIRA)" <jira@apache.org>
To: dev@directory.apache.org
Subject: [jira] Commented: (DIRMINA-119) Multiple selector loops
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    [ http://issues.apache.org/jira/browse/DIRMINA-119?page=comments#action_12357389 ] 

dave irving commented on DIRMINA-119:
-------------------------------------

Hi,

I've been out of the office for a couple of days, and have a few meetings this afternoon.
However, I'll try and take a look over the weekend, or maybe early next week - and I'll post a patch to this issue as soon as I can.

Thanks,

Dave

> Multiple selector loops
> -----------------------
>
>          Key: DIRMINA-119
>          URL: http://issues.apache.org/jira/browse/DIRMINA-119
>      Project: Directory MINA
>         Type: Improvement
>     Versions: 0.9
>  Environment: All. Benefit is dependant on environment
>     Reporter: dave irving
>     Assignee: Trustin Lee
>     Priority: Minor
>  Attachments: prototype.zip
>
> Mina's SocketIoProcessor currently owns a Selector and employs a single Worker to run the NIO "selector loop".
> I have been running tests where Im trying to maximise throughput and have found - that in certain multi-cpu environments - this worker thread can encounter a large amount of starvation even though CPU usage is fairly low.
> By testing 2 selector-loops instead of 1, I managed to improve my overall test throughput by just under 30%.
> The general idea is to do this:
> - Each SocketIoProcessor.Worker encapsulates its own work queues associated Selector
> - It should be possible to configure the number of Workers (and thus selectors) employed by SocketIoProcessor
> - When a SocketSession is added to the SocketIoProcessor, a Worker is selected (round-robin) which will be associated with the SocketSession for its lifetime. This association is managed by SocketSession (get/setWorker)
> - When someone asks SocketIoProcessor to do some work to a session, instead of doing it directly, the processor now asks the session for its Worker, and delegates to the worker (i.e, the same worker is always used for an individual session)
> I've done some prototyping, and have also checked that the concept works with the latest build.
> The prototype is very hacky - mainly because there are some refactoring issues i'd like feed-back on before I submit a "proper" patch for review. Namely:
> - How do you want me to tell the SocketIoProcessor how many workers to use? One option is a system property - but thats pretty hacky. I dont think we need to support changing the number of workers after operation has begun (It'll probably be a function of the number of available CPUs) - and this makes the code simpler. However, as SocketIoProcessor is a (non lazy created) singleton, we need a way to get the param in. We could refactor, or maybe introduce a ProcessorOptions class or something. The SocketIoProcessor could interrigate this when initializing. Any direction on your desired approach would be appreciated
> Cheers,
> Dave 

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