What launcher is Open MPI using?
ssh when it is available, falling back to rsh when ssh cannot be found in the $PATH. But note that Open MPI closes the ssh (or rsh) sessions when the MPI job starts for scalability reasons. This means that the built-in SSH X forwarding tunnels will be shut down before the xterms can be launched. Although it is possible to force Open MPI to keep its SSH connections active (to keep the X tunneling available), we recommend using non-SSH-tunneled X connections, if possible (see below). • In non-rsh/ssh environments (such as when using resource managers), the environment of the process invoking mpirun may be copied to all nodes. In this case, the DISPLAY environment variable may not be suitable. • Some operating systems default to disabling the X11 server from listening for remote/network traffic. For example, see this post on the user’s mailing list, describing how to enable network access to the X11 on Fedora Linux. • There may be intermediate firewalls or other network blocks that preven
