[Opensim-users] Rationale for limiting number of listeners

[Justin Clark-Casey]

I think the chief impact of increasing those numbers will be to increase the number of events being generated.  The more 
listeners you have, the more events.  This means more CPU use and more memory churn (which means more garbage collection 
events and potential main scene loop thread delays, which manifests as rubberbanding).

That said, the performance impact may not be too bad, particularly if fewer listeners means more events squeezed through 
those listeners anyway.  I suggest just trying it to see.  You can get some sense of the number of events being 
generated via the "xengine status" console command - you're probably already seeing high numbers already if you're 
hitting maximum allowed listeners.

On 07/04/13 16:31, Dr Ramesh Ramloll wrote:
> Hello,
> I was wondering if anyone can explain or throw in a few ideas on the motivation for limiting the number of listeners on
> a sim.
> http://opensimulator.org/wiki/Configuring_Scripting
>
>   * max_listens_per_region - Change the max number of llListens per region. Default is 1000.
>   * max_listens_per_script - Change the max number of llListens per script. Default is 64.
>
>
> I have one application which I modified to take into account the max_listens per script which is 64.
> After changing it, the application grew happily again until it is now hitting the max_listens_per_region.
> I have some thought on how I may further reduce the number of listeners I use, but am wondering whether it might be a
> waste of time.
> For e.g. I could further reduce the number of listeners by making sure every object/3d entity I use does not have more
> than one listener. However, I will then need to queue up messages that go between the various objects and squeeze
> everything through only one listener channel ... rather than have data flow between parallel listener channels. Right
> now, every object use two parallel listener channels. I do not yet know the impact on performance between the two
> approaches. What do you think?
> Now question comes up, say, I double max_listens_per_region, what do I stand to lose by doing so?
> Sorry for the questions .... which might be nooby, but I cannot examine underlying opensim infrastructure to find out.
> Am far more focused on application layers.
> --
> 'Consider how the lilies grow. They do not labor or spin.'
> *Rameshsharma Ramloll* PhD, CEO CTO DeepSemaphore LLC, Affiliate /Research Associate Professor/, Idaho State University,
> Pocatello, ID 83209 Tel: 208-240-0040
> Blog <http://deepsemaphore.posterous.com/>, LinkedIn <http://www.linkedin.com/in/rameshramloll>, DeepSemaphore LLC
> <http://www.deepsemaphore.com>, Google+ profile <https://plus.google.com/103652369558830540272/about>
>
>
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Justin Clark-Casey (justincc)
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