17.2.119. MPI_File_iwrite

MPI_File_iwrite - Writes a file starting at the location specified by the individual file pointer (nonblocking, noncollective).

17.2.119.1. SYNTAX

17.2.119.1.1. C Syntax

#include <mpi.h>

int MPI_File_iwrite(MPI_File fh, const void *buf, int count,
     MPI_Datatype datatype, MPI_Request *request)

17.2.119.1.2. Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_IWRITE(FH, BUF, COUNT, DATATYPE, REQUEST, IERROR)
     <type>  BUF(*)
     INTEGER FH, COUNT, DATATYPE, REQUEST, IERROR

17.2.119.1.3. Fortran 2008 Syntax

USE mpi_f08
MPI_File_iwrite(fh, buf, count, datatype, request, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
     INTEGER, INTENT(IN) :: count
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     TYPE(MPI_Request), INTENT(OUT) :: request
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

17.2.119.2. INPUT/OUTPUT PARAMETER

  • fh: File handle (handle).

17.2.119.3. INPUT PARAMETERS

  • buf: Initial address of buffer (choice).

  • count: Number of elements in buffer (integer).

  • datatype: Data type of each buffer element (handle).

17.2.119.4. OUTPUT PARAMETER

  • request: Request object (handle).

  • IERROR: Fortran only: Error status (integer).

17.2.119.5. DESCRIPTION

MPI_File_iwrite is a nonblocking version of the MPI_File_write interface. It attempts to write into the file associated with fh (at the current individual file pointer position maintained by the system) a total number of count data items having datatype type from the user’s buffer buf. The data is written into those parts of the file specified by the current view. MPI_File_iwrite stores the number of datatype elements actually written in status. All other fields of status are undefined.

It is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified when the file was open.

17.2.119.6. ERRORS

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

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_INIT / MPI_INIT_THREAD, after MPI_FINALIZE, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_COMM_SET_ERRHANDLER on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_COMM_SPAWN[_MULTIPLE]. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

In the sessions model, the error handler can be set during MPI_Session_init.

Open MPI includes three predefined error handlers that can be used:

MPI_ERRORS_ARE_FATAL: Causes the program to abort all connected MPI processes.
MPI_ERRORS_ABORT:     An error handler that can be invoked on a communicator,
                      window, file, or session. When called on a communicator, it
                      acts as if MPI_ABORT was called on that communicator. If
                      called on a window or file, acts as if MPI_ABORT was called
                      on a communicator containing the group of processes in the
                      corresponding window or file. If called on a session,
                      aborts only the local process.
MPI_ERRORS_RETURN:    Returns an error code to the application.

MPI applications can also implement their own error handlers.

Custom MPI error handlers can be created by calling: MPI_Comm_create_errhandler(3) MPI_File_create_errhandler(3) MPI_Session_create_errhandler(3) MPI_Win_create_errhandler(3)

Predefined and custom error handlers can be set by calling: MPI_Comm_set_errhandler(3) MPI_File_set_errhandler(3) MPI_Session_set_errhandler(3) MPI_Win_set_errhandler(3)

Note that MPI does not guarantee that an MPI program can continue past an error.

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3 standard for more information.