MPI_FILE_GET_GROUP(3)

💅 MPI_FILE_GET_GROUP(3) — an Open MPI glow-up 🦋

okay bestie, welcome to the MPI_FILE_GET_GROUP page from the Open MPI manual set — yes this is a section 3 manpage, and yes we're gonna make it make sense 💖

✨ NAME ✨

MPI_File_get_group — returns a duplicate of the process group of a file. like, a whole copy, not a borrow 🎀

🌸 SYNTAX 🌸

💜 C Syntax

#include <mpi.h>

int MPI_File_get_group(MPI_File fh, MPI_Group *group)

💜 Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_GET_GROUP(FH, GROUP, IERROR)
     INTEGER FH, GROUP, IERROR

💜 Fortran 2008 Syntax

USE mpi_f08
MPI_File_get_group(fh, group, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     TYPE(MPI_Group), INTENT(OUT) :: group
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

🍓 INPUT PARAMETER 🍓

• fh — the file handle, aka the little handle for the file we're talking about (type: handle) 🫶

🧚 OUTPUT PARAMETERS 🧚

• group — the group that opened the file (type: handle). this is the duplicate, bestie, it's yours now 💅
• ierror — Fortran only: the error status (integer). classic Fortran behaviour, we respect it 😌

🔥 DESCRIPTION 🔥

so MPI_File_get_group returns a duplicate of the group of the communicator that was used to open the file associated with fh. that duplicated group comes back to you in group. ✨

and here's the part where you gotta be a responsible main character: the user is responsible for freeing group, using MPI_Group_free. no cap, don't just leave it lying around 💀

🌈 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. periodt. 💖

before that error value gets 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. ngl that's a lot but it all matters 🎀

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 make it fatal 💀
• 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. iconic scoping, honestly 👑
• MPI_ERRORS_RETURN — returns an error code to the application. the chill one 🦋

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, no promises 😭

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. iykyk 📚

👑 COPYRIGHT 👑

2003-2026, The Open MPI Community

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and that's the whole vibe check, bestie — this page is from the Open MPI manual, dated Sep 11, 2026, and it slays. go free that group 🫶✨🌸