MPI_File_read_ordered_begin(3) Open MPI MPI_File_read_ordered_begin(3)NAMEMPI_File_read_ordered_begin - Reads a file at a location specified by a
shared file pointer; beginning part of a split collective routine (non‐
blocking).
SYNTAX
C Syntax
#include <mpi.h>
int MPI_File_read_ordered_begin(MPI_File fh, void *buf,
int count, MPI_Datatype datatype)
Fortran Syntax
INCLUDE 'mpif.h'
MPI_FILE_READ_ORDERED_BEGIN(FH, BUF, COUNT, DATATYPE, IERROR)
<type> BUF(*)
INTEGER FH, COUNT, DATATYPE, IERROR
C++ Syntax
#include <mpi.h>
void MPI::File::Read_ordered_begin(void* buf, int count,
const MPI::Datatype& datatype)
INPUT/OUTPUT PARAMETER
fh File handle (handle).
INPUT PARAMETERS
count Number of elements in buffer (integer).
datatype Data type of each buffer element (handle).
OUTPUT PARAMETERS
buf Initial address of buffer (choice).
IERROR Fortran only: Error status (integer).
DESCRIPTIONMPI_File_read_ordered_begin is the beginning part of a split collec‐
tive, nonblocking routine that must be called by all processes in the
communicator group associated with the file handle fh. Each process
may pass different argument values for the datatype and count argu‐
ments. Each process attempts to read, from the file associated with fh,
a total number of count data items having datatype type into the user's
buffer buf. For each process, the location in the file at which data
is read is the position at which the shared file pointer would be after
all processes whose ranks within the group are less than that of this
process had read their data.
NOTES
All the nonblocking collective routines for data access are "split"
into two routines, each with _begin or _end as a suffix. These split
collective routines are subject to the semantic rules described in Sec‐
tion 9.4.5 of 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++ func‐
tions 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.
1.7.4 Feb 04, 2014 MPI_File_read_ordered_begin(3)
