Troubleshooting MPI failure to start on OSX

On some versions of OSX, users have reported issues with MPI processes failing to start. This problem can be identified as it causes errors of the kind

[[20648,0],0] bind() failed on error Address already in use

It appears a solution for this is simply to run:

export TMPDIR=/tmp

Then to run VSimComposer from the same terminal.

Another occasional problem shows up with the following error:

Fatal error in internal_Init: Other MPI error, error stack:

Followed by lengthy error output.

One solution is to add the following to /etc/hosts or /private/etc/hosts : yourMachineName

Where yourMachineName is the name of your machine