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MPI_Comm_spawn_multiple(3) man page (version 1.2.9)

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       MPI_Comm_spawn_multiple  - Spawns multiple binaries, or the same binary
       with multiple sets of arguments.


C Syntax

       #include <mpi.h>
       int MPI_Comm_spawn_multiple(int count, char *array_of_commands[],
            char **array_of_argv[], int array_of_maxprocs[], MPI_Info
            array_of_info[], int root, MPI_Comm comm, MPI_Comm *intercomm,
            int array_of_errcodes[])

Fortran Syntax

       INCLUDE 'mpif.h'

C++ Syntax

       #include <mpi.h>
       MPI::Intercomm MPI::Intracomm::Spawn_multiple(int count,
            const char* array_of_commands[], const char** array_of_argv[],
            const int array_of_maxprocs[], const MPI::Info array_of_info[],
            int root, int array_of_errcodes[])

       MPI::Intercomm MPI::Intracomm::Spawn_multiple(int count,
            const char* array_of_commands[], const char** array_of_argv[],
            const int array_of_maxprocs[], const MPI::Info array_of_info[],
            int root)


       count     Number of commands (positive integer, significant to MPI only
                 at root -- see NOTES).

                 Programs  to  be executed (array of strings, significant only
                 at root).

                 Arguments for commands (array of array of strings,   signifi-
                 cant only at root).

                 Maximum  number of processes to start for each command (array
                 of integers, significant only at root).

                 Info objects telling the runtime  system  where  and  how  to
                 start processes (array of handles, significant only at root).

       root      Rank of process in  which  previous  arguments  are  examined
                 spawned group (handle).

                 One code per process (array of integers).

       IERROR    Fortran only: Error status (integer).


       MPI_Comm_spawn_multiple  is  identical to MPI_Comm_spawn except that it
       can specify multiple executables. The first argument, count,  indicates
       the  number  of executables. The next three arguments are arrays of the
       corresponding  arguments  in   MPI_Comm_spawn.   The   next   argument,
       array_of_info,  is  an array of info arguments; however, only the first
       argument in that array is used.  Any subsequent arguments in the  array
       are  ignored because an info argument applies to the entire job that is
       spawned, and cannot be different for each executable in the  job.   See
       the INFO ARGUMENTS section for more information.

       For    the    Fortran    version    of   array_of_argv,   the   element
       array_of_argv(i,j) is the jth argument to command number i.

       In any language, an application may  use  the  constant  MPI_ARGVS_NULL
       (which  is  likely to be (char ***)0 in C) to specify that no arguments
       should be passed to any commands. The effect of setting individual ele-
       ments  of  array_of_argv  to  MPI_ARGV_NULL  is not defined. To specify
       arguments for some commands but not others, the commands without  argu-
       ments  should  have  a  corresponding  argv whose first element is null
       ((char *)0 in C and empty string in Fortran).

       All of the spawned processes have the same MPI_COMM_WORLD. Their  ranks
       in  MPI_COMM_WORLD  correspond  directly to the order in which the com-
       mands are specified in MPI_Comm_spawn_multiple.  Assume  that  m1  pro-
       cesses  are  generated by the first command, m2 by the second, etc. The
       processes corresponding to the first command have ranks 0, 1,..., m1-1.
       The  processes in the second command have ranks m1, m1+1, ..., m1+m2-1.
       The processes in the third have ranks m1+m2, m1+m2+1, ...,  m1+m2+m3-1,

       The array_of_errcodes argument is 1-dimensional array of size

             _ count
            \       n ,
            /_ i=1   i

       where  i is the ith element of array_of_maxprocs. Command number i cor-
       responds to the i contiguous slots in this array from element

                             _              _
             _ i-1          |   _ i          |
            \       n ,  to |  \      n      | -1
            /_ j=1   i      |  /_ j=1  j     |
                            |_              _|

       Error codes are treated as for MPI_Comm_spawn.

       host                  char *    Host on which the process should be spawned.
       wdir                  char *    Directory where the executable is located.

       Note that in Open MPI 1.2, the first array location in array_of_info is
       applied to all the commands in array_of_commands.


       The  argument  count  is  interpreted  by  MPI  only at the root, as is
       array_of_argv. Since the leading dimension of array_of_argv is count, a
       nonpositive  value of count at a nonroot node could theoretically cause
       a runtime bounds check  error,  even  though  array_of_argv  should  be
       ignored  by the subroutine. If this happens, you should explicitly sup-
       ply a reasonable value of count on the nonroot nodes.

       Calling MPI_Comm_spawn many times would create many  sets  of  children
       with different MPI_COMM_WORLDs, whereas MPI_Comm_spawn_multiple creates
       children with a single MPI_COMM_WORLD, so the two methods are not  com-
       pletely  equivalent.  Also   if you need to spawn multiple executables,
       you may get better performance by using MPI_Comm_spawn_multiple instead
       of calling MPI_Comm_spawn several times.


       Almost  all MPI routines return an error value; C routines as the value
       of the function and Fortran routines in the last  argument.  C++  func-
       tions  do  not  return  errors.  If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before  the  error  value is returned, the current MPI error handler is
       called. By default, this error handler aborts the MPI job,  except  for
       I/O   function   errors.   The   error  handler  may  be  changed  with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
       may  be  used  to cause error values to be returned. Note that MPI does
       not guarantee that an MPI program can continue past an error.



Open MPI 1.2 September 200MPI_Comm_spawn_multiple(3OpenMPI)

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