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MPI_Comm_dup

:ref:`MPI_Comm_dup` |mdash| Duplicates an existing communicator with all its cached information.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Comm_dup(MPI_Comm comm, MPI_Comm *newcomm)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'

MPI_COMM_DUP(COMM, NEWCOMM, IERROR)
    INTEGER COMM, NEWCOMM, IERROR

Fortran 2008 Syntax

USE mpi_f08

MPI_Comm_dup(comm, newcomm, ierror)
    TYPE(MPI_Comm), INTENT(IN) :: comm
    TYPE(MPI_Comm), INTENT(OUT) :: newcomm
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER

  • comm : Communicator (handle).

OUTPUT PARAMETERS

  • newcomm : Copy of comm (handle).
  • ierror : Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_Comm_dup` duplicates the existing communicator comm with associated key values. For each key value, the respective copy callback function determines the attribute value associated with this key in the new communicator; one particular action that a copy callback may take is to delete the attribute from the new communicator. Returns in newcomm a new communicator with the same group, any copied cached information, but a new context (see the "Functionality" subsection of the "Caching" section in the "Groups, Contexts, and Communicators" chapter in the MPI Standard).

NOTES

This operation is used to provide a parallel library call with a duplicate communication space that has the same properties as the original communicator. This includes any attributes (see below) and topologies (see the "Process Topologies" chapter in the MPI Standard). This call is valid even if there are pending point-to-point communications involving the communicator comm. A typical call might involve an :ref:`MPI_Comm_dup` at the beginning of the parallel call, and an :ref:`MPI_Comm_free` of that duplicated communicator at the end of the call. Other models of communicator management are also possible. This call applies to both intra- and intercommunicators. Note that it is not defined by the MPI standard what happens if the attribute copy callback invokes other MPI functions. In Open MPI, it is not valid for attribute copy callbacks (or any of their children) to add or delete attributes on the same object on which the attribute copy callback is being invoked.

ERRORS

.. seealso:: :ref:`MPI_Comm_dup_with_info`