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

       USE MPI
       ! or the older form: 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.