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MPI_File_set_atomicity(3OpenMPI)                                            MPI_File_set_atomicity(3OpenMPI)



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.




Open MPI 1.2                                   September 2006               MPI_File_set_atomicity(3OpenMPI)