MPI_Comm_spawn(3)

NAME
     MPI_Comm_spawn - Starts a number of MPI processes and establishes
     communication with them, returning an intercommunicator

SYNOPSIS
     C:

          #include <mpi.h>

          int MPI_Comm_spawn( command, argv, maxprocs, info, root,
          comm, intercomm, array_of_errcodes )
          int  maxprocs, root, array_of_errcodes[];
          char *command,*argv[];
          MPI_Comm comm,*intercomm;
          MPI_Info info;


     Fortran:

          INCLUDE "mpif.h" (or USE MPI)

          INTEGER info, maxprocs, root, comm, intercomm,
          array_of_errcodes(*), ierror
          CHARACTER*(*) command, argv(*)

          CALL MPI_COMM_SPAWN(command, argv, maxprocs, info, root,
          comm, intercomm, array_of_errcodes, ierror)


DESCRIPTION
     The MPI_Comm_spawn routine tries to start maxprocs identical copies of
     the MPI program specified by command, establishing communication with
     them and returning an intercommunicator.  The spawned processes are
     referred to as childern.  The children have their own MPI_COMM_WORLD,
     which is separate from the of the parents.  This call is collective over
     comm.  This routine accepts the following parameters:

     command        Specifies the name of the MPI program to be spawned
                    (string, significant only at root).

     argv           Specifies arguments to be passed to command.
                    MPI_ARGV_NULL should be used if no arguments are to be
                    passed to the program (array of strings, significant only
                    at root).

     maxprocs       Specifies the maximum number of processes to start
                    (integer, significant only at root).

     info           A set of key-value pairs telling the runtime system where
                    and how to start the processes.  Currently this value is
                    ignored.  MPI_INFO_NULL should be used if no info argument
                    is supplied (handle, significant only at root).
     root           The rank of the process in which previous arguments are
                    examined (integer).

     comm           The intracommunicator containg the group of spawning
                    processes (handle).

     intercomm      Upon return, the intercommunicator between the original
                    group and the newly spawned group (handle).

     array_of_errcodes
                    Upon return, reports the status of the spawned program,
                    one code per process.  MPI_ERRCODES_IGNORE should be used
                    if no argument is provided (array of integers).

     ierror         Specifies the return code value for successful completion,
                    which is in MPI_SUCCESS.  MPI_SUCCESS is defined in the
                    mpif.h file (integer).

NOTES
     In this implementation, all of the spawned processes have access to
     stdout and stderr.   However, none of the spawned processes have access
     to stdin.

     The argv argument is an array of strings containing arguments that are
     passed to the program.  The first element of argv is the first argument
     passed to command, not, as is conventional in some contexts, the command
     itself.  The argument list is terminated by NULL in C and an empty string
     in FORTRAN.

     Error codes are the values returned by MPI routines (in C) or in the
     ierror argument (in Fortran).  These can be converted to error classes by
     using the MPI_Error_class(3) routine.

SEE ALSO
     MPI_Comm_spawn_multiple(3), MPI_Comm_get_parent(3)

     mpi(1), mpirun(1)