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MPI_Waitsome - 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 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 MPI_Waitany man page,
but using MPI_Waitsome.
CALL MPI_COMM_SIZE(comm, size, ierr)
CALL MPI_COMM_RANK(comm, rank, ierr)
IF(rank .GT. 0) THEN ! client code
DO WHILE(.TRUE.)
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 WHILE(.TRUE.)
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, 0, 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 MPI_Waitsome,
if one or more requests generate an MPI exception, only the first MPI request
that caused an exception will be passed to its corresponding error handler.
No other error handlers will be invoked (even if multiple requests generated
exceptions). However, all requests that generate an exception will have
a relevant error code set in the corresponding status.MPI_ERROR field (unless
MPI_STATUSES_IGNORE was used).
The default 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 generated the MPI 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.
If the invoked error handler allows MPI_Waitsome
to return to the caller, the value MPI_ERR_IN_STATUS will be returned in
the C and Fortran bindings. In C++, if the predefined error handler MPI::ERRORS_THROW_EXCEPTIONS
is used, the value MPI::ERR_IN_STATUS will be contained in the MPI::Exception
object. The MPI_ERROR field can then be examined in the array of returned
statuses to determine exactly which request(s) generated an exception.
MPI_Comm_set_errhandler
MPI_File_set_errhandler
MPI_Test
MPI_Testall
MPI_Testany
MPI_Testsome
MPI_Wait
MPI_Waitall
MPI_Waitany
MPI_Win_set_errhandler
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