# MPI_Comm_get_parent

## NAME

MPI_Comm_get_parent − Returns the parent intercommunicator of current spawned process.

## SYNTAX

## C Syntax

#include <mpi.h>
int MPI_Comm_get_parent(MPI_Comm *parent)

## Fortran Syntax

INCLUDE ’mpif.h’
MPI_COMM_GET_PARENT(PARENT, IERROR)

| INTEGER |  |  | PARENT, IERROR

## C++ Syntax

#include <mpi.h>
static MPI::Intercomm MPI::Comm::Get_parent()

## OUTPUT PARAMETERS

| parent |  | The parent communicator (handle). |
| IERROR |  | Fortran only: Error status (integer). |

## DESCRIPTION

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

If the process was not spawned, MPI_Comm_get_parent returns MPI_COMM_NULL.

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

## NOTES

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

## ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions 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.

## SEE ALSO

MPI_Comm_spawn
MPI_Comm_spawn_multiple

MPI API Index