NAME

       MPI_Mprobe - Blocking matched probe for a message.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Mprobe(int source, int tag, MPI_Comm comm,
            MPI_Message *message, MPI_Status *status)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_MPROBE(SOURCE, TAG, COMM, MESSAGE, STATUS, IERROR)
            INTEGER   SOURCE, TAG, COMM, MESSAGE
            INTEGER   STATUS(MPI_STATUS_SIZE), IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Mprobe(source, tag, comm, message, status, ierror)
            INTEGER, INTENT(IN) :: source, tag
            TYPE(MPI_Comm), INTENT(IN) :: comm
            TYPE(MPI_Message), INTENT(OUT) :: message
            TYPE(MPI_Status) :: status
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       There is no C++ binding for this function.

INPUT PARAMETERS

       source    Source rank or MPI_ANY_SOURCE (integer).

       tag       Tag value or MPI_ANY_TAG (integer).

       comm      Communicator (handle).

OUTPUT PARAMETERS

       message   Message (handle).

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       Like  MPI_Probe  and  MPI_Iprobe, the MPI_Mprobe and MPI_Improbe operations allow incoming messages to be
       queried without actually receiving them, except that MPI_Mprobe and MPI_Improbe provide  a  mechanism  to
       receive  the  specific  message  that  was  matched  regardless  of  other  intervening  probe or receive
       operations.  This gives the application an opportunity to decide how to receive the message, based on the
       information returned by the probe.  In particular, the application may allocate memory  for  the  receive
       buffer according to the length of the probed message.

       A  matching  probe  with  MPI_PROC_NULL  as  source returns message = MPI_MESSAGE_NO_PROC, and the status
       object returns source = MPI_PROC_NULL, tag = MPI_ANY_TAG, and count = 0.

       When MPI_Mprobe returns (from a non-MPI_PROC_NULL source), the matched message can then  be  received  by
       passing the message handle to the MPI_Mrecv or MPI_Imrecv functions.

NOTE

       This is an MPI-3 function and has no C++ binding.

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.

       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_Improbe
       MPI_Probe
       MPI_Iprobe
       MPI_Mrecv
       MPI_Imrecv
       MPI_Cancel

4.1.6                                             Sep 30, 2023                                     MPI_Mprobe(3)