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MPI_Wait(3) man page (version 1.2.9)

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NAME

       MPI_Wait - Waits for an MPI send or receive to complete.

SYNTAX


C Syntax

       #include <mpi.h>
       int MPI_Wait(MPI_Request *request, MPI_Status *status)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_WAIT(REQUEST, STATUS, IERROR)
            INTEGER   REQUEST, STATUS(MPI_STATUS_SIZE), IERROR

C++ Syntax

       #include <mpi.h>
       void Request::Wait(Status& status)

       void Request::Wait()

INPUT PARAMETER

       request   Request (handle).

OUTPUT PARAMETERS

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       A  call to MPI_Wait returns when the operation identified by request is
       complete. If the communication object associated with this request  was
       created by a nonblocking send or receive call, then the object is deal-
       located by the call to MPI_Wait  and  the  request  handle  is  set  to
       MPI_REQUEST_NULL.

       The  call  returns,  in status, information on the completed operation.
       The content of the  status  object  for  a  receive  operation  can  be
       accessed  as  described in Section 3.2.5 of the MPI-1 Standard, "Return
       Status." The status object for a send operation may  be  queried  by  a
       call  to  MPI_Test_cancelled  (see  Section  3.8 of the MPI-1 Standard,
       "Probe and Cancel").

       If your application does not need to examine the status field, you  can
       save  resources by using the predefined constant MPI_STATUS_IGNORE as a
       special value for the status argument.

       One is allowed to call MPI_Wait with a null or inactive  request  argu-
       ment. In this case the operation returns immediately with empty status.

NOTES

       Successful return of MPI_Wait after an MPI_Ibsend implies that the user
       send  buffer can be reused  i.e., data has been sent out or copied into

           CALL MPI_COMM_RANK(comm, rank, ierr)
           IF(rank.EQ.0) THEN
               CALL MPI_ISEND(a(1), 10, MPI_REAL, 1, tag, comm, request, ierr)
               **** do some computation ****
               CALL MPI_WAIT(request, status, ierr)
           ELSE
               CALL MPI_IRECV(a(1), 15, MPI_REAL, 0, tag, comm, request, ierr)
               **** do some computation ****
               CALL MPI_WAIT(request, status, ierr)
           END IF

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++  func-
       tions  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,          MPI_File_set_errhandler,           or
       MPI_Win_set_errhandler (depending on the type of MPI handle that gener-
       ated the request); 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.

       Note that per MPI-1 section 3.2.5, MPI exceptions on requests passed to
       MPI_WAIT  do not set the status.MPI_ERROR field in the returned status.
       The error code is passed to the  back-end  error  handler  and  may  be
       passed  back  to the caller through the return value of MPI_WAIT if the
       back-end error handler returns it.  The pre-defined MPI  error  handler
       MPI_ERRORS_RETURN exhibits this behavior, for example.

SEE ALSO

       MPI_Comm_set_errhandler
       MPI_File_set_errhandler
       MPI_Test
       MPI_Testall
       MPI_Testany
       MPI_Testsome
       MPI_Waitall
       MPI_Waitany
       MPI_Waitsome
       MPI_Win_set_errhandler

Open MPI 1.2                      March 2007                MPI_Wait(3OpenMPI)

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