Segmentation fault with vtkGeometryFilter on 4 threads

Dear Experts,

I have a vtu file containing a mesh composed of hexahedrons and polyhedrons. When I try to use vtkGeometryFilter() on this data it results in segmentation fault. I have included a MWE via python that can be downloaded form (

I know that the vtkGeometryFilter() has been threaded, so when I set number of threads to 1, 2, or 3 using OMP_NUM_THREADS I do not face any problem, but when the number of threads is set to more than 4, I get segmentation fault. This behavior can be replicated on CentOS7 and Fedora 30 machines using the recent VTK release that ships with ParaView 5.9.

Have I stumbled upon a potential bug ?

PS: I was not able to attach a file as I am a new user to this forum (“Sorry, new users can not upload attachments.”), hence the vtu and python were uploaded to

Yes, I believe that this is the bug you encountered, which Timothée has identified and is fixing now:

Wow this must be the quickest response that I have got on any development forum!!! Thank you for this quick response. I will wait for the fix. :slightly_smiling_face:


I have tested the fix proposed by Timothée Couble (, I confirm that it solves the issues that I was facing.

Thank you Will Schroeder for pointing me towards the fix.

Excellent thanks for letting us know

thanks for the information.