MPI_Waitsome(3OpenMPI)													    MPI_Waitsome(3OpenMPI)

NAME

       MPI_Waitsome - Waits for some given communications to complete.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Waitsome(int incount, MPI_Request *array_of_requests,
	    int *outcount, int *array_of_indices,
	    MPI_Status *array_of_statuses)

Fortran Syntax
       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

C++ Syntax
       #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[])

INPUT PARAMETERS

       incount	 Length of array_of_requests (integer).

       array_of_requests
		 Array of requests (array of handles).

OUTPUT PARAMETERS

       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).

DESCRIPTION

       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  allo-
       cated 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 commu-
       nication. 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_STA-
       TUSES_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

NOTES

       The array of indices are in the range 0 to incount-1 for C and in the range 1 to incount for Fortran.

ERRORS

       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  excep-
       tions).	 However,  all requests that generate an exception will have a relevant error code set in the corresponding status.MPI_ERROR field
       (unless MPI_IGNORE_STATUSES 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_errhan-
       dler,  MPI_File_set_errhandler,	or MPI_Win_set_errhandler (depending on the type of MPI handle that generated the MPI request); the prede-
       fined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an  MPI  pro-
       gram 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.

SEE ALSO

       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

Open MPI 1.2							  September 2006					    MPI_Waitsome(3OpenMPI)