:ref:`MPI_Waitsome` |mdash| Waits for some given communications to complete.
#include <mpi.h>
int MPI_Waitsome(int incount, MPI_Request array_of_requests[],
int *outcount, int array_of_indices[],
MPI_Status array_of_statuses[])
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WAITSOME(INCOUNT, ARRAY_OF_REQUESTS, OUTCOUNT,
ARRAY_OF_INDICES, ARRAY_OF_STATUSES, IERROR)
INTEGER INCOUNT, ARRAY_OF_REQUESTS(*), OUTCOUNT
INTEGER ARRAY_OF_INDICES(*)
INTEGER ARRAY_OF_STATUSES(MPI_STATUS_SIZE*)
INTEGER IERROR
USE mpi_f08
MPI_Waitsome(incount, array_of_requests, outcount, array_of_indices,
array_of_statuses, ierror)
INTEGER, INTENT(IN) :: incount
TYPE(MPI_Request), INTENT(INOUT) :: array_of_requests(incount)
INTEGER, INTENT(OUT) :: outcount, array_of_indices(*)
TYPE(MPI_Status) :: array_of_statuses(*)
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
incount
: Length of array_of_requests (integer).array_of_requests
: Array of requests (array of handles).
outcount
: Number of completed requests (integer).array_of_indices
: Array of indices of operations that completed (array of integers).array_of_statuses
: Array of status objects for operations that completed (array of status).ierror
: Fortran only: Error status (integer).
Waits until at least one of the operations associated with active handles in the list have completed. Returns in outcount the number of requests from the list array_of_requests that have completed. Returns in the first outcount locations of the array array_of_indices the indices of these operations (index within the array array_of_requests; the array is indexed from 0 in C and from 1 in Fortran). Returns in the first outcount locations of the array array_of_status the status for these completed operations. If a request that completed was allocated by a nonblocking communication call, then it is deallocated, and the associated handle is set to MPI_REQUEST_NULL.
If the list contains no active handles, then the call returns immediately with outcount = MPI_UNDEFINED.
When one or more of the communications completed by :ref:`MPI_Waitsome` fails, then it is desirable to return specific information on each communication. The arguments outcount, array_of_indices, and array_of_statuses will be adjusted to indicate completion of all communications that have succeeded or failed. The call will return the error code MPI_ERR_IN_STATUS and the error field of each status returned will be set to indicate success or to indicate the specific error that occurred. The call will return MPI_SUCCESS if no request resulted in an error, and will return another error code if it failed for other reasons (such as invalid arguments). In such cases, it will not update the error fields of the statuses.
If your application does not need to examine the array_of_statuses field, you can save resources by using the predefined constant MPI_STATUSES_IGNORE can be used as a special value for the array_of_statuses argument.
Example: Same code as the example in the :ref:`MPI_Waitany` man page, but using :ref:`MPI_Waitsome`.
CALL MPI_COMM_SIZE(comm, size, ierr)
CALL MPI_COMM_RANK(comm, rank, ierr)
IF(rank > 0) THEN ! client code
DO
CALL MPI_ISEND(a, n, MPI_REAL, 0, tag, comm, request, ierr)
CALL MPI_WAIT(request, status, ierr)
END DO
ELSE ! rank=0: server code
DO i=1, size-1
CALL MPI_IRECV(a(1,i), n, MPI_REAL, i, tag, &
comm, requests(i), ierr)
END DO
DO
CALL MPI_WAITSOME(size, request_list, numdone, &
indices, statuses, ierr)
DO i=1, numdone
CALL DO_SERVICE(a(1, indices(i)))
CALL MPI_IRECV(a(1, indices(i)), n, MPI_REAL, i, tag, &
comm, requests(indices(i)), ierr)
END DO
END DO
END IF
The array of indices are in the range 0 to incount-1 for C and in the range 1 to incount for Fortran.
For each invocation of :ref:`MPI_Waitsome`, if one or more requests
generate an MPI error, only the first MPI request that caused an
error will be passed to its corresponding error handler. No other
error handlers will be invoked (even if multiple requests generated
errors). However, all requests that generate an error will have a
relevant error code set in the corresponding status.MPI_ERROR
field (unless MPI_STATUSES_IGNORE
was used).
If the invoked error handler allows :ref:`MPI_Waitsome` to return to
the caller, the value MPI_ERR_IN_STATUS
will be returned in the C
and Fortran bindings.
.. seealso::
* :ref:`MPI_Comm_set_errhandler`
* :ref:`MPI_File_set_errhandler`
* :ref:`MPI_Test`
* :ref:`MPI_Testall`
* :ref:`MPI_Testany`
* :ref:`MPI_Testsome`
* :ref:`MPI_Wait`
* :ref:`MPI_Waitall`
* :ref:`MPI_Waitany`
* :ref:`MPI_Win_set_errhandler`