Thanks for pointers Joachim.
My purpose in not (yet) to optimize the already parallised parts.
My intention is mainly to investigate parallelization of the OCCT surface meshing part in NetGen.
Your team has previously attempted to do such thing, and according to Matthias:
OCC Surface meshing is not parallelized because we had issues with thread-safety in OpenCascade
Being a long time user of OCCT myself, I would like to evaluate where the "thread-safety issues" of OCCT are, and possibly find workarounds, as far as my capabilities go.
The problem is that the current public GitHub version of NetGen, is obviously not the one your team was using when investigating OCCT parallelized surface meshing.
There are indeed several statements in the code, that are only valid in a mono-thread environment (Console outputs, Mesh updates, ...).