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MPI_Waitall(3)                        MPI                       MPI_Waitall(3)


NAME

       MPI_Waitall -  Waits for all given MPI Requests to complete


SYNOPSIS

       int MPI_Waitall(int count, MPI_Request array_of_requests[],
                      MPI_Status array_of_statuses[])


INPUT PARAMETERS

       count  - list length (integer)
       array_of_requests
              - array of request handles (array of handles)


OUTPUT PARAMETER

       array_of_statuses
              - array of status objects (array of Statuses).  May be
              MPI_STATUSES_IGNORE .


NOTES

       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 array_of_status associated with the requests.  Likewise,
       the MPI_ERROR 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.

NOTES ON THE MPI_STATUS ARGUMENT
       The MPI_ERROR 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 (
       MPI_Testall , MPI_Testsome , MPI_Waitall , and MPI_Waitsome ).  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
       or 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 MPI_SUCCESS for any send or receive operation that completed
       successfully, or MPI_ERR_PENDING for any operation which has neither
       failed nor completed.


THREAD AND INTERRUPT SAFETY

       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.


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 call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
       Fortran.


ERRORS

       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_Comm_set_errhandler (for
       communicators), MPI_File_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 not guarentee that an MPI
       program can continue past an error; however, MPI implementations will
       attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_REQUEST
              - Invalid MPI_Request .  Either null or, in the case of a
              MPI_Start or MPI_Startall , not a persistent request.
       MPI_ERR_ARG
              - Invalid argument.  Some argument is invalid and is not
              identified by a specific error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_IN_STATUS
              - 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 .


LOCATION

       src/mpi/pt2pt/waitall.c

                                   9/20/2012                    MPI_Waitall(3)

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