strange issues with openmpi

[davydden]

i was reinstalling the software stack and used the current openmpi and got this when trying to use it outside of Spack:

$ mpirun -v
PMIx has detected a temporary directory name that results
in a path that is too long for the Unix domain socket:

    Temp dir: /var/folders/5k/sqpp24tx3ylds4fgm13pfht00000gn/T/openmpi-sessions-501@MacBook-Pro-<USER>_0/25440

Try setting your TMPDIR environmental variable to point to
something shorter in length

[davydden]

probably it's something with the new version of openmpi, fixed by setting TMPDIR, no idea why it did not complain before.

[davydden]

there is even a special issue on OpenMPI FAQ https://www.open-mpi.org/faq/?category=osx#startup-errors-with-open-mpi-2.0.x strangely, i never came across this problem before. Either way - it's not related to Spack.

[tgamblin]

@davydden: Mac OS X has some pretty weird, long temp directory names by default. This might not be Spack's fault, but if there is some config file that we could patch in OpenMPI by default, to make it use a shorter tmp name, then we could add that to the package.

The default TMPDIR has the advantage that it is only owned by you, but the OpenMPI guys recommend to set it to /tmp as on other systems, for lack of other options.