MPI_FILE_WRITE_AT_ALL_END(3)

💖 MPI_FILE_WRITE_AT_ALL_END(3) 💖

okay bestie, welcome to the Open MPI girlies manual page, today we're learning about MPI_File_write_at_all_end — she writes a file at explicitly specified offsets, and she's the ending part of a split collective routine (blocking). no cap.

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✨ NAME ✨

MPI_File_write_at_all_end — writes a file at explicitly specified offsets; ending part of a split collective routine (blocking). 🎀

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🌸 SYNTAX 🌸

C Syntax

#include <mpi.h>

int MPI_File_write_at_all_end(MPI_File fh, const void *buf,
     MPI_Status *status)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_WRITE_AT_ALL_END(FH, BUF, STATUS, IERROR)
     <type>  BUF(*)
     INTEGER FH, STATUS(MPI_STATUS_SIZE), IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_File_write_at_all_end(fh, buf, status, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
     TYPE(MPI_Status) :: status
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🦋 INPUT/OUTPUT PARAMETER 🦋

• fh — the file handle, periodt (handle).

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🍓 INPUT PARAMETER 🍓

• buf — initial address of buffer, you know the drill (choice).

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💅 OUTPUT PARAMETERS 💅

• status — status object (status).
• ierror — Fortran only: error status (integer).

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👑 DESCRIPTION 👑

So MPI_File_write_at_all_end is literally the ending part of a split collective routine, and what she does is store the number of elements actually written into the file associated with fh in status. 🫶

The data gets written into those parts of the file specified by the current view. And bestie, listen: all other fields of status are undefined. she's not giving ✨everything✨, just the count. iykyk.

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🔥 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 Section 9.4.5 of the MPI-2 standard. (yes, actual rules, go read them, it's giving homework but we do it for the lore 📚)

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💀 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. so like, check it, always.

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/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.

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

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. dramatic much? 💀
• 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 by calling:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

not me telling you this but: note that MPI does not guarantee that an MPI program can continue past an error. so like, she might not survive it, ok? 😭

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

See the Error Handling section of the MPI-3.1 standard for more information.

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🎀 Copyright 🎀

2003-2026, The Open MPI Community. iconic, we stan. 👑

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aaaand that's the whole page bestie, you ate this. 💖✨🌸🦋 the source is Open MPI, version/date stamp says Sep 10, 2026, and yes this is still MPI_FILE_WRITE_AT_ALL_END(3) the entire time. mwah, go write some files at explicit offsets, main character energy only. 🫶🔥👑