MPI_Waitall - Waits for all given MPI Requests to complete
int MPI_Waitall(int count, MPI_Request array_of_requests,
- - list length (integer)
- - array of request handles (array of handles)
- - array of status objects (array of Statuses). May be
If one or more of the requests completes with an error, MPI_ERR_IN_STATUS
is returned. An error value will be present is elements of
associated with the requests. Likewise, the
field in the status elements associated with requests that
have successfully completed will be MPI_SUCCESS
. Finally, those
requests that have not completed will have a value of MPI_ERR_PENDING
While it is possible to list a request handle more than once in the
array_of_requests, such an action is considered erroneous and may cause the
program to unexecpectedly terminate or produce incorrect results.
field of the status return is only set if the return from
the MPI routine is MPI_ERR_IN_STATUS
. That error class is only
returned by the routines that take an array of status arguments (
). In all other cases, the value of the MPI_ERROR
field in the status is unchanged. See section 3.2.5 in the MPI-1.1
specification for the exact text.
For send operations, the only use of status is for MPI_Test_cancelled
in the case that there is an error in one of the four routines that may return
the error class MPI_ERR_IN_STATUS
, in which case the MPI_ERROR
field of status will be set. In that case, the value will be set to
for any send or receive operation that completed
successfully, or MPI_ERR_PENDING
for any operation which has neither
failed nor completed.
This routine is thread-safe. This means that this routine may be safely used by
multiple threads without the need for any user-provided thread locks. However,
the routine is not interrupt safe. Typically, this is due to the use of memory
allocation routines such as malloc
or other non-MPICH runtime routines
that are themselves not interrupt-safe.
All MPI routines in Fortran (except for MPI_WTIME
have an additional argument ierr
at the end of the argument list.
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
All MPI objects (e.g., MPI_Datatype
) are of type
All MPI routines (except MPI_Wtime
) 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_Comm_set_errhandler
(for files), and MPI_Win_set_errhandler
(for RMA windows). The MPI-1 routine MPI_Errhandler_set
may be used but
its use is deprecated. The predefined error handler MPI_ERRORS_RETURN
may be used to cause error values to be returned. Note that MPI does
guarentee that an MPI program can continue past an error; however,
MPI implementations will attempt to continue whenever possible.
- - 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 ).
- - The actual error value is in the MPI_Status argument. This error
class is returned only from the multiple-completion routines (
MPI_Testall , MPI_Testany , MPI_Testsome ,
MPI_Waitall , MPI_Waitany , and MPI_Waitsome ). The
field MPI_ERROR in the status argument contains the error value or
MPI_SUCCESS (no error and complete) or MPI_ERR_PENDING to
indicate that the request has not completed. The MPI Standard does not
specify what the result of the multiple completion routines is when an
error occurs. For example, in an MPI_WAITALL , does the routine
wait for all requests to either fail or complete, or does it return
immediately (with the MPI definition of immediately, which means
independent of actions of other MPI processes)? MPICH has chosen to make
the return immediate (alternately, local in MPI terms), and to use the
error class MPI_ERR_PENDING (introduced in MPI 1.1) to indicate
which requests have not completed. In most cases, only one request with an
error will be detected in each call to an MPI routine that tests multiple
requests. The requests that have not been processed (because an error
occured in one of the requests) will have their MPI_ERROR field
marked with MPI_ERR_PENDING .