MPI_FILE_READ_ALL_END(3)

💖 MPI_FILE_READ_ALL_END(3) 💖

okay bestie, this is the Open MPI manual page for MPI_File_read_all_end, and it's genuinely such a specific little icon. Let's get into it 🫶

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🌸 NAME 🌸

MPI_File_read_all_end — reads a file starting at the locations specified by individual file pointers; it's the ending part of a split collective routine, and yes it's blocking. periodt.

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✨ SYNTAX ✨

🎀 C Syntax

#include <mpi.h>

int MPI_File_read_all_end(MPI_File fh, void *buf,
     MPI_Status *status)

🎀 Fortran Syntax

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

🎀 Fortran 2008 Syntax

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

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🦋 INPUT/OUTPUT PARAMETER 🦋

• fh — File handle (handle). lowkey the whole personality of this call ngl.

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💅 OUTPUT PARAMETERS 💅

• buf — Initial address of buffer (choice).
• status — Status object (status).
• ierror — Fortran only: error status (integer).

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👑 DESCRIPTION 👑

MPI_File_read_all_end is the ending part of a split collective operation. What it does: it stores the number of elements actually read from the file associated with fh (at the current individual file pointer position, the one maintained by the system) into the user's buffer buf in status. The data is taken out of those parts of the file specified by the current view. 🌈

and heads up babes: all other fields of status are undefined. not "probably fine," not "trust me" — undefined. 💀

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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. iykyk 🧚

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😭 ERRORS 😭

Almost all MPI routines return an error value: C routines hand it back as the return result of the function, and Fortran routines put it 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 the 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 but honest 💀
• 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, it 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, it 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

Note that MPI does not guarantee that an MPI program can continue past an error. so like, plan accordingly bestie 🙈

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

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and that's the whole page, bestie!! this one's from Open MPI and it was dated Sep 10, 2026 — so if you're reading this, slay, you made it all the way to the bottom of MPI_FILE_READ_ALL_END(3). go read a file, collectively, in two halves. main character energy only. ✨🦋💅