17.2.140. MPI_File_set_atomicity

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

17.2.140.1. SYNTAX

17.2.140.1.1. C Syntax

#include <mpi.h>

int MPI_File_set_atomicity(MPI_File fh, int flag)

17.2.140.1.2. Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_SET_ATOMICITY(FH, FLAG, IERROR)
     INTEGER FH, FLAG, IERROR

17.2.140.1.3. 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

17.2.140.2. INPUT PARAMETERS

fh: File handle (handle).
flag: true to enable atomic mode, false to enable nonatomic mode (boolean).

17.2.140.3. OUTPUT PARAMETER

IERROR: Fortran only: Error status (integer).

17.2.140.4. 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.

17.2.140.5. ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

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.