We have found a potential issue with BPROC that may effect Open MPI.
Open MPI by default uses PTYs for I/O forwarding, if PTYs aren't setup on the compute nodes, Open MPI will revert to using pipes. Recently (today) we found a potential issue with PTYs and BPROC. A simple reader/writer using PTYs causes the writer to hang in uninterruptible sleep. The consistency of the process table from the head node and the back end nodes is also effected, that is "bps" shows no writer process, while "bpsh NODE ps aux" shows the writer process in uninterruptible sleep.

Since Open MPI uses PTYs by default on BPROC this results in ORTED or MPI processes being orphaned on compute nodes. The workaround for this issue is to configure Open MPI with --disable-pty-support and rebuild.

- Open MPI Team

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