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MPI_Comm_set_name.3.rst

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MPI_Comm_set_name

:ref:`MPI_Comm_set_name` |mdash| Associates a name with a communicator.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Comm_set_name(MPI_Comm comm, const char *comm_name)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_SET_NAME(COMM, COMM_NAME, IERROR)
     INTEGER COMM, IERROR
     CHARACTER*(*) COMM_NAME

Fortran 2008 Syntax

USE mpi_f08
MPI_Comm_set_name(comm, comm_name, ierror)
     TYPE(MPI_Comm), INTENT(IN) :: comm
     CHARACTER(LEN=*), INTENT(IN) :: comm_name
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT/OUTPUT PARAMETER

  • comm: Communicator whose identifier is to be set (handle).

INPUT PARAMETER

  • comm_name: Character string to be used as the identifier for the communicator (string).

OUTPUT PARAMETER

  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_Comm_set_name` allows a user to associate a name string with a communicator. The character string that is passed to :ref:`MPI_Comm_set_name` is saved inside the MPI library (so it can be freed by the caller immediately after the call, or allocated on the stack). Leading spaces in name are significant, but trailing ones are not.

:ref:`MPI_Comm_set_name` is a local (noncollective) operation, which affects only the name of the communicator as seen in the process that made the :ref:`MPI_Comm_set_name` call. There is no requirement that the same (or any) name be assigned to a communicator in every process where it exists.

The length of the name that can be stored is limited to the value of MPI_MAX_OBJECT_NAME in Fortran and MPI_MAX_OBJECT_NAME-1 in C (to allow for the null terminator). Attempts to set names longer than this will result in truncation of the name. MPI_MAX_OBJECT_NAME must have a value of at least 64.

NOTES

Since :ref:`MPI_Comm_set_name` is provided to help debug code, it is sensible to give the same name to a communicator in all of the processes where it exists, to avoid confusion.

Regarding name length, under circumstances of store exhaustion, an attempt to set a name of any length could fail; therefore, the value of MPI_MAX_OBJECT_NAME should be viewed only as a strict upper bound on the name length, not a guarantee that setting names of less than this length will always succeed.

ERRORS

.. seealso::
   * :ref:`MPI_Comm_get_name`