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


 Fortran 2008 Syntax
USE mpi_f08
MPI_File_set_atomicity(fh, flag, ierror)
 TYPE(MPI_File), INTENT(IN) :: fh
 LOGICAL, INTENT(IN) :: flag
 INTEGER, OPTIONAL, INTENT(OUT) :: ierror


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


 INPUT PARAMETERS
 1i
fh
File handle (handle).
 1i
flag
true to enable atomic mode, false to enable nonatomic mode (boolean).

 OUTPUT PARAMETER
 1i
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.