MPI_COMM_GET_NAME(3)

👑 MPI_COMM_GET_NAME 💅

okay bestie, welcome to the MPI_Comm_get_name page — that's the Open MPI manual, section 3, and honestly it's a lil bop. It does exactly one thing and it does it iconically: it hands you back the name you most recently slapped onto a communicator. That's it. That's the whole vibe. ✨

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🌸 NAME 🌸

MPI_Comm_get_name — returns the name that was most recently associated with a communicator. no cap, that's literally the entire job description 🫶

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🎀 SYNTAX 🎀

C Syntax

#include <mpi.h>

int MPI_Comm_get_name(MPI_Comm comm, char *comm_name, int *resultlen)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_GET_NAME(COMM, COMM_NAME, RESULTLEN, IERROR)
     INTEGER COMM, RESULTLEN, IERROR
     CHARACTER*(*) COMM_NAME

Fortran 2008 Syntax

USE mpi_f08
MPI_Comm_get_name(comm, comm_name, resultlen, ierror)
     TYPE(MPI_Comm), INTENT(IN) :: comm
     CHARACTER(LEN=MPI_MAX_OBJECT_NAME), INTENT(OUT) :: comm_name
     INTEGER, INTENT(OUT) :: resultlen
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

three whole ways to ask for a name, and every single one of them ate 💅

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📥 INPUT PARAMETER 📥

• comm — the communicator whose name you're tryna get back (handle). it's giving "who dis". 🙈

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📤 OUTPUT PARAMETER 📤

• comm_name — the name that was previously stored on the communicator, or an empty string if no such name exists (string). yes, empty string is a valid answer, don't panic. 🍓
• resultlen — length of the returned name (integer).
• ierror — Fortran only: error status (integer).

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💖 DESCRIPTION 💖

So here's the tea, bestie. MPI_Comm_get_name returns the last name that was previously associated with the given communicator. The name can be set and retrieved from any language, and the same name will come back to you no matter which language you used to ask for it. it's giving "language barrier? never met her." 🌈

comm_name should be allocated so that it can hold a resulting string of length MPI_MAX_OBJECT_NAME characters. MPI_Comm_get_name returns a copy of the set name in comm_name. copy, not a reference — she's not lending you her jacket, she's giving you your own jacket. 🧚

If the user has not associated a name with a communicator, or an error occurs, MPI_Comm_get_name will return an empty string (all spaces in Fortran, "" in C). important! errors and "no name" both look like emptiness here, so don't read too much into a blank.

The three predefined communicators will have predefined names associated with them. Thus, the names of MPI_COMM_WORLD, MPI_COMM_SELF, and MPI_COMM_PARENT will have the default of MPI_COMM_WORLD, MPI_COMM_SELF, and MPI_COMM_PARENT. the icons came pre-named, periodt. 👑

And the fact that the system may have chosen to give a default name to a communicator does not prevent the user from setting a name on the same communicator — doing this removes the old name and assigns the new one. so yes, you can absolutely rename her. rebrand era. 🔥

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✨ NOTES ✨

It is safe to simply print the string returned by MPI_Comm_get_name, as it is always a valid string even if there was no name. so like. go ahead and printf it, bestie, it will not betray you. 🫶

Note that associating a name with a communicator has no effect on the semantics of an MPI program, and will (necessarily) increase the store requirement of the program, since the names must be saved. therefore, there is no requirement that users use these functions to associate names with communicators. lowkey it costs you a lil memory and buys you zero behavior change. 💀

However, debugging and profiling MPI applications may be made easier if names are associated with communicators, since the debugger or profiler should then be able to present information in a less cryptic manner. so like… it's giving "for the plot" but the plot is your profiler output and honestly that's a good plot. 🔍

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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. classic.

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.

no fr, that whole paragraph is one sentence in spirit and it's a lot. breathe. 🌬️

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

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. everyone's going down together, no survivors, it's a group activity. 😭
• 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. so it's MPI_Abort but make it situational awareness. 👑
• MPI_ERRORS_RETURN — returns an error code to the application. the chill one. she just hands you the receipt and walks away. 💅

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

build your own, bestie, it's giving DIY era. 🛠️

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-3.1 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! 🎀 thanks for reading the MPI_COMM_GET_NAME(3) page from Open MPI — the Sep 10, 2026 edition, brought to you by The Open MPI Community, copyright 2003-2026. go name your communicators, your profiler will thank you, mwah 💖🌈✨