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MPI_Start.3.rst

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MPI_Start

:ref:`MPI_Start` - Initiates a communication using a persistent request handle.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Start(MPI_Request *request)

Fortran Syntax

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

Fortran 2008 Syntax

USE mpi_f08
MPI_Start(request, ierror)
     TYPE(MPI_Request), INTENT(INOUT) :: request
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER

  • request: Communication request (handle).

OUTPUT PARAMETER

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

DESCRIPTION

A communication (send or receive) that uses a persistent request is initiated by the function :ref:`MPI_Start`.

The argument, request, is a handle returned by one of the persistent communication-request initialization functions (:ref:`MPI_Send_init`, :ref:`MPI_Bsend_init`, :ref:`MPI_Ssend_init`, :ref:`MPI_Rsend_init`, MPI_Recv_init). The associated request should be inactive and becomes active once the call is made.

If the request is for a send with ready mode, then a matching receive should be posted before the call is made. From the time the call is made until after the operation completes, the communication buffer should not be accessed.

The call is local, with semantics similar to the nonblocking communication operations (see Section 3.7 in the MPI-1 Standard, "Nonblocking Communication.") That is, a call to :ref:`MPI_Start` with a request created by :ref:`MPI_Send_init` starts a communication in the same manner as a call to :ref:`MPI_Isend`; a call to :ref:`MPI_Start` with a request created by :ref:`MPI_Bsend_init` starts a communication in the same manner as a call to :ref:`MPI_Ibsend`; and so on.

ERRORS

.. seealso::
   * :ref:`MPI_Bsend_init`
   * :ref:`MPI_Rsend_init`
   * :ref:`MPI_Send_init`
   * MPI_Sssend_init
   * :ref:`MPI_Recv_init`
   * :ref:`MPI_Startall`