During the discussion of MPI-2 functionality, it was pointed out by Aurelien that there was an inherent race condition between startup of ompi-server and mpirun. Specifically, if someone started ompi-server to run in the background as part of a script, and then immediately executed mpirun, it was possible that an MPI proc could attempt to contact the server (or that mpirun could try to read the server's contact file before the server is running and ready.
At that time, we discussed createing a new tool "ompi-wait-server" that would wait for the server to be running, and/or probe to see if it is running and return true/false. However, rather than create yet another tool, it seemed just as effective to add the functionality to mpirun.
Thus, this commit creates two new mpirun cmd line flags (hey, you can never have too many!):
--wait-for-server : instructs mpirun to ping the server to see if it responds. This causes mpirun to execute an rml.ping to the server's URI with an appropriate timeout interval - if the ping isn't successful, mpirun attempts it again.
--server-wait-time xx : sets the ping timeout interval to xx seconds. Note that mpirun will attempt to ping the server twice with this timeout, so we actually wait for twice this time. Default is 10 seconds, which should be plenty of time.
This has only lightly been tested. It works if the server is present, and outputs a nice error message if it cannot be contacted. I have not tested the race condition case.
This commit was SVN r19152.
7342a6f1da