gmsh report error "signal only works in main thread"

[YuanWenqing]

I'm not familiar with gmsh and I want to use pygmsh to subdivide mesh in a grpc request. But it seems gmsh limits multi-threading support in default.

  ...
  File "gmshutil.py", line 22, in subdivide_obj
    mesh = geom.generate_mesh()
  File "python3.6/site-packages/pygmsh/common/geometry.py", line 54, in __exit__
    gmsh.finalize()
  File "python3.6/site-packages/gmsh.py", line 261, in finalize
    signal.signal(signal.SIGINT, oldsig)
  File "python3.6/signal.py", line 47, in signal
    handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
ValueError: signal only works in main thread

I read http://gmsh.info/doc/texinfo/gmsh.html and tried solutions in #317

gmsh.option.setNumber('General.NumThreads', 32)
# OR
gmsh.option.setNumber('Mesh.Algorithm3D', 32)

But problem's not solved.

Could somebody help?

[thisistheplace]

Upvoted. I have the same error calling gmsh from FastAPI endpoints. I'm guessing the server is using the main thread and the error comes about when gmsh is executed in a worker thread. Will let you know if I get anywhere :)

[JTHesse]

@thisistheplace were you able to fix the error?

[thisistheplace]

Hi, I ended up running gmsh in a separate process to the server and using a messaging queue.

E.g. gmsh gets called in this line:

https://github.com/thisistheplace/joint_model/blob/ab3aa2985908846698d6358c3a51dc56dbee738a/src/app/server/worker/worker.py#L84

[JTHesse]

Thanks for the response. I will try that!