MPI synchronisation freezes in ca 1% of simulations

[FilipDominec]

There is some deadlock in the python-meep HDF export or sync() function; I am suspicious it is the multiprocessing communication. The simulation silently hangs after the FDTD timestepping is finished and has to be terminated manually.

Observed on Ubuntu 16.04 with openmpi 1.10.2. This never happened to me on previous versions of Ubuntu, although I used a very similar installation procedure for python meep (https://github.com/FilipDominec/python-meep-install).

Currently, I have no clue how to resolve this except for debugging openmpi, which is beyond my capabilities.