[simspark-devel] about multi-thread implementation

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

Hi Hedayat and all,

I take a look at current multi-thread implementation.
But I can not understand it exactly, could you help me?

1). in simulationserver.cpp
00491             Step();
00492             ControlEvent(CE_EndCycle);
The Step() calls mSceneServer->Pre/PostPhysicsUpdate() again,
I think it is redundant, what should be called maybe
mSceneServer->PhysicsUpdate(mSimStep),
right?

Place ControlEvent(CE_EndCycle) here is for rendering function in the
main thread?
The original code can not work with Mesa-6.4.1, it can work with
Mesa-6.5.21 and ATI fglrx 8.31.5 .
I checked the ChanegeLog of Mesa, there are some bug-fixes of thread
safe in Mesa-6.5.
Can you test that?

2). Synchronization by the barrier just make all the threads run one
by one, it is not the real parallel.
The original idea is make SimControlNodes run parallel, and
PhysicsUpdate can also run at the same time.
Since the scene tree can be used as cache.
PrePhysicsUpdate copy data from scene tree to ODE,  PosPhysicsUpdate
copy data from ODE to scene tree.
PhysicsUpdate only effects ODE internal data.

( To Joschka,
Sorry, I do not finished the document work about single-thread and multi-thread.
I want to make things clear firstly.)

-- 
Best wishes!

Xu Yuan
School of Automation
Southeast University, Nanjing, China

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