MPI_Comm_get_parent.3.rst

MPI_Comm_get_parent

:ref:`MPI_Comm_get_parent` |mdash| Returns the parent intercommunicator of current spawned process.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Comm_get_parent(MPI_Comm *parent)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_GET_PARENT(PARENT, IERROR)
     INTEGER PARENT, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Comm_get_parent(parent, ierror)
     TYPE(MPI_Comm), INTENT(OUT) :: parent
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

OUTPUT PARAMETERS

• parent: The parent communicator (handle).
• ierror: Fortran only: Error status (integer).

DESCRIPTION

If a process was started with :ref:`MPI_Comm_spawn` or :ref:`MPI_Comm_spawn_multiple`, :ref:`MPI_Comm_get_parent` returns the "parent" intercommunicator of the current process. This parent intercommunicator is created implicitly inside of :ref:`MPI_Init` and is the same intercommunicator returned by the spawn call made in the parents.

If the process was not spawned, :ref:`MPI_Comm_get_parent` returns MPI_COMM_NULL.

After the parent communicator is freed or disconnected, :ref:`MPI_Comm_get_parent` returns MPI_COMM_NULL.

NOTES

:ref:`MPI_Comm_get_parent` returns a handle to a single intercommunicator. Calling :ref:`MPI_Comm_get_parent` a second time returns a handle to the same intercommunicator. Freeing the handle with :ref:`MPI_Comm_disconnect` or :ref:`MPI_Comm_free` will cause other references to the intercommunicator to become invalid (dangling). Note that calling :ref:`MPI_Comm_free` on the parent communicator is not useful.

ERRORS

.. seealso::
   * :ref:`MPI_Comm_spawn`
   * :ref:`MPI_Comm_spawn_multiple`