MPI_File_preallocate - Preallocates storage space for a
       file


SYNOPSIS

       C:

            #include "mpi.h"

            int MPI_File_preallocate(MPI_File fh, MPI_Offset size)

       Fortran:

            INCLUDE "mpif.h" (or USE MPI)

            INTEGER fh, ierror
            INTEGER(KIND=MPI_OFFSET_KIND) size

            CALL MPI_FILE_PREALLOCATE(fh, size, ierror)


DESCRIPTION

       MPI_File_preallocate ensures that storage space is
       allocated for the first size bytes of the file associated
       with fh.

       The MPI_File_preallocate routine accepts the following
       arguments:

       fh        Specifies the file handle (handle)

       size      Specifies the size to preallocate (nonnegative
                 integer)

       ierror    Specifies the return code value for successful
                 completion, which is in MPI_SUCCESS.
                 MPI_SUCCESS is defined in the mpif.h file.

       MPI_File_preallocate is collective; all processes in the
       group must pass identical values for size. Regions of the
       file that have been written previously are unaffected.
       For newly allocated regions of the file,
       MPI_File_preallocate has the same effect as writing
       undefined data.  If size is larger than the current file
       size, the file size increases to size.  If size is less
       than or equal to the current file size, the file size is
       unchanged.

       The treatment of file pointers, pending nonblocking
       accesses, and file consistency is the same as with
       MPI_File_set_size.  If MPI_MODE_SEQUENTIAL mode was
       specified when the file was opened, it is erroneous to
       call this routine.

       expensive.

   Notes for Fortran
       All MPI objects (for example, MPI_Datatype, MPI_Comm,
       MPI_File) are of type INTEGER.


SEE ALSO

       MPI_File_open(3), MPI_File_set_size(3), MPI_IO(3)


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