int MPI_File_set_atomicity(
  MPI_File mpi_fh,
  int flag
);

Parameters

mpi_fh

[in] file handle (handle)

flag

[in] true to set atomic mode, false to set nonatomic mode (logical)

Remarks

Let FH be the set of file handles created by one collective open. The consistency semantics for data access operations using FH is set by collectively calling MPI_FILE_SET_ATOMICITY on FH. MPI_FILE_SET_ATOMICITY is collective; 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.

Changing the consistency semantics for an open file only affects new data accesses. All completed data accesses are guaranteed to abide by the consistency semantics in effect during their execution. Nonblocking data accesses and split collective operations that have not completed (e.g., via MPI_WAIT) are only guaranteed to abide by nonatomic mode consistency semantics.

Example Code

The following sample code illustrates MPI_File_set_atomicity.

Insert code here.