MPI_COMM_SET_INFO(3)

📦
version 5.0.11 · 16 versions
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💅 MPI_COMM_SET_INFO — like, the Open MPI glow-up for your communicator's info hints 🎀

Okay bestie, welcome to MPI_COMM_SET_INFO(3) from Open MPI — yes the manual page, yes the whole thing, no I did not skip a single option, iykyk ✨

🌸 SYNTAX 🌸

C Syntax

#include <mpi.h>

int MPI_Comm_set_info(MPI_Comm comm, MPI_Info info)

Fortran Syntax 🧚

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_SET_INFO(COMM, INFO, IERROR)
     INTEGER COMM, INFO, IERROR

Fortran 2008 Syntax 🦋

USE mpi_f08
MPI_Comm_set_info(comm, info, ierror)
     TYPE(MPI_Comm), INTENT(IN) :: comm
     TYPE(MPI_Info), INTENT(IN) :: info
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

🍓 INPUT PARAMETERS 🍓

  • comm — the communicator that's about to get its info hints set. it's giving "main character communicator" energy, honestly 👑
  • info — the MPI_Info object holding the hints you're gonna slap onto comm. this is the whole personality update, fr fr 💖

🌈 OUTPUT PARAMETERS 🌈

  • ierror — Fortran only, bestie! it's the error status, and it's an integer. that's it, that's the whole vibe check 💅

✨ DESCRIPTION ✨

So MPI_Comm_set_info sets new values for the hints of the communicator associated with comm. cute, right? but plot twist: MPI_Comm_set_info is a collective routine 😭 everybody's in on it.

Now — the info object may be different on each process. Yes, you read that right, each process can have its own little info moment. But — and this is the crucial part, don't come for me — any info entries that an implementation requires to have identical values on all processes must appear with the same value in each process's info object. no cap. mismatched values there and it's not slaying anymore 💀

The following info key assertions may be accepted by Open MPI:

  • mpi_assert_no_any_tag (boolean): if set to true, then the implementation may assume that the process will not use the MPI_ANY_TAG wildcard on the given communicator 🙈
  • mpi_assert_no_any_source (boolean): if set to true, then the implementation may assume that the process will not use the MPI_ANY_SOURCE wildcard on the given communicator 🫶
  • mpi_assert_exact_length (boolean): if set to true, then the implementation may assume that the lengths of messages received by the process are equal to the lengths of the corresponding receive buffers, for point-to-point communication operations on the given communicator 🌸
  • mpi_assert_allow_overtaking (boolean): if set to true, then the implementation may assume that point-to-point communications on the given communicator do not rely on the non-overtaking rule specified in MPI-3.1 Section 3.5. In other words (translating for the girlies 🎀): the application asserts that send operations are not required to be matched at the receiver in the order in which the send operations were performed by the sender, and receive operations are not required to be matched in the order in which they were performed by the receiver. iconic behavior, truly ⭐
bestie warning: these are assertions. you're promising the implementation something. don't lie to it, ok? 🙏

💀 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. literally every single one, periodt.

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. yeah. all of them. 💀
  • 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. situational, we love that for it 💅
  • MPI_ERRORS_RETURN — returns an error code to the application. polite. respectful. 🎀

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… don't count on it, 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. 🔥

💜 SEE ALSO 💜

  • MPI_Comm_get_info
  • MPI_Info_create
  • MPI_Info_set
  • MPI_Info_free

(the whole info-object friend group, honestly — go read them too 🫶)

2003-2026, The Open MPI Community

and that's the page, bestie! 🦋 written in Sep 11, 2026 edition vibes, brought to you by MPI_COMM_SET_INFO(3) from the Open MPI fam — now go set some info hints and slay ✨💖🎀

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