On Apr 22, 2014, at 4:58 PM, Jeff Hammond <[email protected]> wrote:

PMI is specific to MPICH-family, right? The problem that was observed had to do with MPICH/OpenMPI mixing. 'mpirun -np 2' led to two copies of the application running in serial...

I'm pretty sure that Open MPI can speak some flavors of PMI. I don't have any personal experience with using that functionality though, so it may not be very automagical. It might require some special build flags or run-time config. So keep that in mind when considering solutions. Also, don't forget that the "singleton init" case is supported by both OMPI and MPICH, so the absence of PMI_* vars isn't sufficient for you to decide that you were launched by some other MPI implementation's process manager. You actually have to check for other common variables from other launchers / MPI implementations and warn that you know you cannot handle them. I feel like we've had this conversation before on the MPICH lists and decided there was no good solution for this problem... hah, here it is: http://lists.mcs.anl.gov/pipermail/mpich-discuss/2012-February/011756.html I completely concede that Jed's correct here in his response (modulo the "Open MPI is system-installed on Macs", which is no longer true for modern Macs): http://lists.mcs.anl.gov/pipermail/mpich-discuss/2012-February/011757.html -Dave