MPI_WIN_FREE(3)

🌸 NAME 🌸

MPI_Win_free — frees the window object and returns a null handle. This is the MPI_WIN_FREE(3) page from the Open MPI manual, bestie 💖.

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✨ SYNTAX ✨

💻 C Syntax 💻

#include <mpi.h>

int MPI_Win_free(MPI_Win *win)

🧚 Fortran Syntax 🧚

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WIN_FREE(WIN, IERROR)
               INTEGER WIN, IERROR

🦋 Fortran 2008 Syntax 🦋

USE mpi_f08
MPI_Win_free(win, ierror)
               TYPE(MPI_Win), INTENT(INOUT) :: win
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🫶 INPUT/OUTPUT PARAMETER 🫶

• win — window object (handle). It goes in, and the handle comes back as a null handle, periodt ✨.

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💅 OUTPUT PARAMETER 💅

• ierror — Fortran only: Error status (integer).

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🦋 DESCRIPTION 🦋

Okay so MPI_Win_free frees the window object win and returns a null handle — equal to MPI_WIN_NULL, no cap 💅.

This is a collective call, and it is executed by all processes in the group associated with win. The vibe check here is real: a process can invoke it only after it has completed its involvement in RMA communications on window win — that is, the process has called MPI_Win_fence, or called MPI_Win_unlock to match a previous call to MPI_Win_lock. When the call returns, the window memory can be freed. Slay, but only in that order 🌈.

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🎀 NOTES 🎀

If the window was created through MPI_Win_allocate or MPI_Win_allocate_shared, then the memory buffer allocated in that call will be freed when calling MPI_Win_free. That’s the little bonus cleanup moment 🧚✨.

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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. Bestie, that’s just how MPI does it 😭.

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. Very dramatic, very final 💀.
• 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

Note that MPI does not guarantee that an MPI program can continue past an error. That’s a big caveat, bestie — don’t assume the program can just keep vibing after an error 🫶.

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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🔍 SEE ALSO 🔍

• MPI_Win_create
• MPI_Win_allocate
• MPI_Win_allocate_shared

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👑 COPYRIGHT 👑

2003-2026, The Open MPI Community.

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xoxo, your Open MPI bestie 💖 — source/version: Open MPI; date: Sep 11, 2026. MPI_WIN_FREE(3), out 🎀✨.