[vtkusers] Multi threading question

[Matthias Riechmann]

I have a similar question: When triggering all rendering by yourself it 
is easy to protect VTK from concurrent access by using a mutex. But how 
can I do that when using a QVtkWidget? In this case the rendering might 
be triggered at any time from the GUI. Is there a way to do a 
synchronisation from a application programmer's view in this scenario?


Matthias




David E DeMarle schrieb:
> What you are doing is correct. VTK is not thread safe, so in general
> you have to protect against concurrent access manually as you have
> done.
> 
> On Mon, Feb 23, 2009 at 10:51 PM, Anton Deguet <anton.deguet at jhu.edu> wrote:
>> Hello,
>>
>> I have an application with one renderer and multiple actors.  Each actor (assembly) is controlled by a different thread and all use a single renderer (running in its own thread).  As a temporary solution, I use an application wide mutex lock/unlock for any access to VTK to avoid rendering while a thread is modifying the scene via its actor (threads can modify anything; position, size, visibility, opacity, texture, ... and other non atomic operations).  It somewhat works but I am afraid one programmer might forget to lock/unlock the scene before modifying its actors and this might be hard to debug/detect.  I am also slightly concerned by long waiting periods to lock the mutex as the application is growing.
>>
>> So, does VTK provide something better than what I am using, i.e. is there any build-in thread safety mechanism that one can use (multiple buffers, queued commands, ...) that would avoid locks.
>>
>> Thank you,
>>
>> Anton Deguet
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> 
> 

-- 
Dipl.-Inform. Matthias Riechmann
Institut für Prozessrechentechnik, Automation und Robotik
Medizin-Gruppe
Universität Karlsruhe (TH)
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