Threading Deadlock?

[Stucuk]

Im wondering if the following could cause 2 threads to Deadlock. Thread B calls the NewtonUpdate every 1/60th of a second. When there is a callback from Newton its syncronised to Thread A. My concern is if Thread A tries to do something with Newton while Thread B is doing the NewtonUpdate that Thread A would then be Waiting for Thread B to finish. So if a callback is called, then Thread B would wait for Thread A, which in Turn is waiting on Thread B.

Thread B

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Repeat

  Lock;
   FTimer.Refresh;
   UpdateWorld(FTimer.FrameTime); //We start the NewtonUpdate
   ...


Thread A

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NewtonThread.Lock; //Waits for Thread B as its currently Locked.
...


Newton Sends Callback to Thread B Which then Tries to Sync with Thread A

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procedure TNewtonThread.PhysicsSetTransform(const body : PNewtonBody; const matrix : TMatrix; Forwardto : Pointer);
begin
 FBody         := Body;
 FMatrix       := Matrix;
 FForwardTo    := ForwardTo;
 FForwardType  := ftPhysicsSetTransform;
 Synchronize(ForwardProc); //Deadlock?
end;

If im correct ill have to do it a more annoying way where every Class that can have physics and be rendered will have to have Critical Sections.

[Julio Jerez]

do not wrroied abpu thread locking the engien try to take case of tha intenally.
whe you get a callback, the only time you will have to lock is if teh callback write to data that is part of a different callback.

[Stucuk]

The locks arn't Newton's. There custom Critical Sections ( EnterCriticalSection() ) to stop the Main Thread from trying to access Newton while its being updated by the NewtonThread Thread.

[Julio Jerez]

critical section do not intefate with each other. onless they sue the same handle.
you cans lock teh tread and notion will pass the critical section inlcuding Netwon.
you should be ok.

[Stucuk]

They are the same Handle, Both locks in the sample code use the same Critical Section. Im not using Newton's own Critical Sections. What newton does isn't at question, its my bad concept of putting newton in a separate thread with the least amount of critical sections thats at question.