Re: [simspark-devel] Countdown for Atlanta

[Yuan X. <xuy...@gm...>]

Hi Markus,

Thanks for your reminder.
After some changes, the server runs faster!
The server can keep running when 10 agents connected, but with incorrect timing.
I will do more test then, and try to have a look at stack problem.

>
> I think we already have a full copy of the scene state that is relevant
> to physics: The ODE library itself holds all relevant state ;-)
>
> Therefore it should be possible to run the physics thread in parallel.
> Possible conflicts only arise when the new ODE state is written back to
> the scene graph. At this point we have to wait for other threads to
> become ready.
>
> The point from which the physics thread could run in parallel lies
> within the SceneServer::Update() method _after_ the call to
> PrePhysicsUpdate(). From this point on the collision handling and
> stepping of the world relies entirely on the internal ODE state.
> Therefore both steps could be run in parallel to e.g. the OpenGL thread.
>
> The collision handling runs mostly within ODE code. Excpetions are the
> collision callbacks that may modify the scene in turn. The most common
> Collisionhandler nodes are the ContactJointHandler. This nodes calls the
>   dJointAttach ODE function and should therefore be no problem.
>
> Other collision handler nodes are derived from the recorder handler that
> collects collision events for further processing within the node itself.
> The collected information is ususally only referenced after the physics
> update, e.g. from the SoccerRuleAspect or some sensor implementation.
>
> If other threads don't modify the ODE state while the physics thread
> runs, there should be no problem. However as ODE is quite stack hungry,
> we might have to increase the stack size manually in the pyhsics thread
> [1,2].
>
> Cheers,
> Markus
>
> [1] http://thread.gmane.org/gmane.comp.lib.ode/12094/focus=12095
> [2]
> http://news.gmane.org/find-root.php?message_id=%3c7dfa3e5505081812185ce79b97%40mail.gmail.com%3e
>


-- 
Best wishes!

Xu Yuan
School of Automation
Southeast University, Nanjing, China

mail:   xuy...@gm...
          xy...@ya...
web:   http://xuyuan.cn.googlepages.com
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