NAME

MPI_Comm_free - Mark a communicator object for deallocation.

SYNTAX

C Syntax

#include <mpi.h>
int MPI_Comm_free(MPI_Comm *comm)

Fortran Syntax

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

Fortran 2008 Syntax

USE mpi_f08
MPI_Comm_free(comm, ierror)
	TYPE(MPI_Comm), INTENT(INOUT) :: comm
	INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

#include <mpi.h>
void Comm::Free()

INPUT PARAMETER

comm: Communicator to be destroyed (handle).

OUTPUT PARAMETER

IERROR: Fortran only: Error status (integer).

DESCRIPTION

This operation marks the communicator object for deallocation. The handle is set to MPI_COMM_NULL. Any pending operations that use this communicator will complete normally; the object is actually deallocated only if there are no other active references to it. This call applies to intracommunicators and intercommunicators. Upon actual deallocation, the delete callback functions for all cached attributes (see Section 5.7 in the MPI-1 Standard, "Caching") are called in arbitrary order.

NOTES

Note that it is not defined by the MPI standard what happens if the delete_fn callback invokes other MPI functions. In Open MPI, it is not valid for delete_fn callbacks (or any of their children) to add or delete attributes on the same object on which the delete_fn callback is being invoked.

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.