MPI_File_set_atomicity(3)          Open MPI          MPI_File_set_atomicity(3)



NAME
       MPI_File_set_atomicity - Sets consistency semantics for data-access
       operations (collective).


SYNTAX
       C Syntax
           #include <mpi.h>
           int MPI_File_set_atomicity(MPI_File fh, int flag)

       Fortran Syntax
           INCLUDE 'mpif.h'
           MPI_FILE_SET_ATOMICITY(FH, FLAG, IERROR)
                  INTEGER    FH, FLAG, IERROR


C++ Syntax
       #include <mpi.h>
       void MPI::File::Set_atomicity(bool flag)


INPUT PARAMETERS
       fh        File handle (handle).

       flag      true to enable atomic mode, false to enable nonatomic mode
                 (boolean).


OUTPUT PARAMETER
       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       The consistency semantics for data-access operations using the set of
       file handles created by one collective MPI_File_open is set by
       collectively calling MPI_File_set_atomicity. All processes in the group
       must pass identical values for fh and flag.  If flag is true, atomic
       mode is set; if flag is false, nonatomic mode is set.

       The default value on a call to MPI_File_open in Open MPI is true for
       jobs running on more than one node, false for jobs running on a single
       SMP. For more information, see the MPI-2 standard.


ERRORS
       Almost all MPI routines return an error value; C routines as the value
       of the function and Fortran routines in the last argument. C++
       functions do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before the error value is returned, the current MPI error handler is
       called. For MPI I/O function errors, the default error handler is set
       to MPI_ERRORS_RETURN. The error handler may be changed with
       MPI_File_set_errhandler; the predefined error handler
       MPI_ERRORS_ARE_FATAL may be used to make I/O errors fatal. Note that
       MPI does not guarantee that an MPI program can continue past an error.




1.4.1                            Jan 14, 2010        MPI_File_set_atomicity(3)
