Adding support for mpiexec as well as mpirun.

The mpiexec command is the preferred way of starting MPI jobs.  We also
support mpirun for backwards compatiblity.

IPython/kernel/scripts/ipcluster.py

@@ -513,7 +513,8 b' def main_local(args):'
     dstart.addErrback(lambda f: f.raiseException())
 
 
-def main_mpirun(args):
+def main_mpi(args):
+    print vars(args)
     cont_args = []
     cont_args.append('--logfile=%s' % pjoin(args.logdir,'ipcontroller'))
 
@@ -524,7 +525,7 b' def main_mpirun(args):'
     cl = ControllerLauncher(extra_args=cont_args)
     dstart = cl.start()
     def start_engines(cont_pid):
-        raw_args = ['mpirun']
+        raw_args = [args.cmd]
         raw_args.extend(['-n',str(args.n)])
         raw_args.append('ipengine')
         raw_args.append('-l')
@@ -665,7 +666,7 b' def get_args():'
     
     parser_mpirun = subparsers.add_parser(
         'mpirun',
-        help='run a cluster using mpirun',
+        help='run a cluster using mpirun (mpiexec also works)',
         parents=[base_parser]
     )
     parser_mpirun.add_argument(
@@ -674,7 +675,20 b' def get_args():'
         dest="mpi", # Don't put a default here to allow no MPI support
         help="how to call MPI_Init (default=mpi4py)"
     )
-    parser_mpirun.set_defaults(func=main_mpirun)
+    parser_mpirun.set_defaults(func=main_mpi, cmd='mpirun')
+
+    parser_mpiexec = subparsers.add_parser(
+        'mpiexec',
+        help='run a cluster using mpiexec (mpirun also works)',
+        parents=[base_parser]
+    )
+    parser_mpiexec.add_argument(
+        "--mpi",
+        type=str,
+        dest="mpi", # Don't put a default here to allow no MPI support
+        help="how to call MPI_Init (default=mpi4py)"
+    )
+    parser_mpiexec.set_defaults(func=main_mpi, cmd='mpiexec')
     
     parser_pbs = subparsers.add_parser(
         'pbs', 

docs/source/parallel/parallel_process.txt

@@ -85,33 +85,40 b' To see other command line options for the local mode, do::'
 
     $ ipcluster local -h
 
-Using :command:`ipcluster` in mpirun mode
------------------------------------------
+Using :command:`ipcluster` in mpiexec/mpirun mode
+-------------------------------------------------
 
-The mpirun mode is useful if you:
+The mpiexec/mpirun mode is useful if you:
 
 1. Have MPI installed.
-2. Your systems are configured to use the :command:`mpirun` command to start 
-   processes.
+2. Your systems are configured to use the :command:`mpiexec` or
+   :command:`mpirun` commands to start MPI processes.
+
+.. note::
+
+    The preferred command to use is :command:`mpiexec`.  However, we also 
+    support :command:`mpirun` for backwards compatibility.  The underlying
+    logic used is exactly the same, the only difference being the name of the 
+    command line program that is called.
 
 If these are satisfied, you can start an IPython cluster using::
 
-    $ ipcluster mpirun -n 4
+    $ ipcluster mpiexec -n 4
 
 This does the following:
 
 1. Starts the IPython controller on current host.
-2. Uses :command:`mpirun` to start 4 engines.
+2. Uses :command:`mpiexec` to start 4 engines.
 
 On newer MPI implementations (such as OpenMPI), this will work even if you don't make any calls to MPI or call :func:`MPI_Init`.  However, older MPI implementations actually require each process to call :func:`MPI_Init` upon starting.  The easiest way of having this done is to install the mpi4py [mpi4py]_ package and then call ipcluster with the ``--mpi`` option::
 
-    $ ipcluster mpirun -n 4 --mpi=mpi4py
+    $ ipcluster mpiexec -n 4 --mpi=mpi4py
 
 Unfortunately, even this won't work for some MPI implementations.  If you are having problems with this, you will likely have to use a custom Python executable that itself calls :func:`MPI_Init` at the appropriate time.  Fortunately, mpi4py comes with such a custom Python executable that is easy to install and use.  However, this custom Python executable approach will not work with :command:`ipcluster` currently.
 
 Additional command line options for this mode can be found by doing::
 
-    $ ipcluster mpirun -h
+    $ ipcluster mpiexec -h
 
 More details on using MPI with IPython can be found :ref:`here <parallelmpi>`.