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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)
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
#include <mpi.h>
static int Request::Waitsome(int incount, Request
array_of_requests[], int array_of_indices[], Status array_of_statuses[])
static int Request::Waitsome(int incount, Request
array_of_requests[], int array_of_indices[])
- 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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