I got a segmentation fault running the attached code.
https://ngsolve.org/media/kunena/attachments/758/mpi_periodic.py
https://ngsolve.org/media/kunena/attachments/758/mpi_periodic.py
with this output message:
Fatal error in PMPI_Waitall: See the MPI_ERROR field in MPI_Status for the error code
Attachment: mpi_periodic.py