Crash using BRepAlgoAPI_Common in Multithreading

charles meyer
Wed, 05/29/2024 - 12:35

Forums:

Hello everyone,

I'm trying to do overlap detections on 3D models utilizing BRepAlgoAPI_Common with OpenCascade 7.8.1.
To enhance efficiency, I've ventured into running these computations within a multithreaded environment.
Rather than utilizing SetRunParallel to process a single BRepAlgoAPI_Common in multiple threads, I've opted for employing numerous BRepAlgoAPI_Common within each thread.

To ensure data integrity, I've encapsulated my TopoDS_Shapes within mutexes to prevent concurrent access.

However, I've encountered crashes with certain models. I've attempted to protect the TopoDS_TShape instead of the TopoDS_Shapes, yet the crashes persist.

Is BRepAlgoAPI_Common inherently thread-safe, or are there known challenges when employing it within a multithreaded context ?

Thank you!

Best Regards

Charles Meyer

Dmitrii Pasukhin
Wed, 05/29/2024 - 13:22

Hello, if operation take impact on original Face, for sure, it will be data raysing.

For avoid that you need to make deep clone original shape. And after that match before/after with ReShape and history of clone operation.

Best regards, Dmitrii.

charles meyer
Wed, 05/29/2024 - 15:33

Hello Dmitrii,

Thank you for your quick answer.

I tried to make deep clone with BRepBuilderAPI_Copy but i still got the crash.
Is that the good way to deep clone a shape ?

Thanks

Dmitrii Pasukhin
Wed, 05/29/2024 - 19:00

It is only one way if you have no option to control data sharing behavior.

I have no idea why you have crash... Do you copy geometry too? Which level you split your common operation? Face level? Solid level?

Best regards, Dmitrii.

charles meyer
Thu, 05/30/2024 - 09:49

I am copying the shape at the solid level.

Is there a specific detail or subtlety we might be missing that could explain why the crash is still occurring?

Thanks again for your help.

Best regards,

Charles Meyer

Dmitrii Pasukhin
Thu, 05/30/2024 - 10:09

When you using copy tool. BRepBuilderAPI_Copy you need to specificy any arguments to true.

Best regards, Dmitrii.

charles meyer
Fri, 05/31/2024 - 12:25

It turns out that my issue was due to having compiled OCCT with the BUILD_RELEASE_DISABLE_EXCEPTIONS flag set to ON.
After recompiling with this flag set to OFF, I no longer experience crashes.

Thanks again for your help.

Best regards, Charles Meyer