Waits for any specified send or receive to complete
MPI_Status *status )
|count ||list length (integer)
|array_of_requests ||array of requests (array of handles)
|index ||index of handle for operation that completed (integer). In the
range 0 to count-1. In Fortran, the range is 1 to count.
|status ||status object (Status)
If all of the requests are MPI_REQUEST_NULL, then index is returned as
MPI_UNDEFINED, and status is returned as an empty status.
Note on status for send operations
For send operations, the only use of status is for MPI_Test_cancelled or
in the case that there is an error, in which case the MPI_ERROR field of
status will be set.
Notes for Fortran
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have
an additional argument ierr at the end of the argument list. ierr
is an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with the
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER
All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value;
C routines as the value of the function and Fortran routines in the last
argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with MPI_Errhandler_set; the predefined error handler
MPI_ERRORS_RETURN may be used to cause error values to be returned.
Note that MPI does not guarentee that an MPI program can continue past
- No error; MPI routine completed successfully.
- Invalid MPI_Request. Either null or, in the case of a
MPI_Start or MPI_Startall, not a persistent request.
- Invalid argument. Some argument is invalid and is not
identified by a specific error class (e.g., MPI_ERR_RANK).