MPI_Session_set_errhandler(3)

🎀 MPI_Session_set_errhandler 💖

okay so bestie, this is a page from the MPI manual — and today's main character is MPI_Session_set_errhandler. it's the glow-up your session's error handling deserves ✨

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✨ NAME ✨

MPI_Session_set_errhandler — Set MPI session error handler 💅

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🌸 SYNOPSIS 🌸

int MPI_Session_set_errhandler(MPI_Session session, MPI_Errhandler errhandler)

like… two args, one job, zero drama 🫶

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🦋 INPUT PARAMETERS 🦋

• session — the session, bestie. it's a handle 🎀
• errhandler — the new error handler for that session. also a handle. swap in the new vibe 🔥

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💜 THREAD AND INTERRUPT SAFETY 💜

ngl this part is the serious part, so listen up 🌈

This routine is thread and interrupt safe only if no MPI routine that updates or frees the same MPI object may be called concurrently with this routine.

The MPI standard defined a thread-safe interface but this does not mean that all routines may be called without any thread locks. For example, two threads must not attempt to change the contents of the same MPI_Info object concurrently. The user is responsible in this case for using some mechanism, such as thread locks, to ensure that only one thread at a time makes use of this routine.

fr fr, one thread at a time on the same object or it's giving chaos 😭🔒

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💀 NOTES FOR FORTRAN 💀

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an additional argument ierr at the end of the argument list. ierr is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement.

All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran.

like, yes, everything is INTEGER, that's just the Fortran era 💅

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🌟 ERRORS 🌟

All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job 😭. The error handler may be changed with MPI_Comm_set_errhandler (for communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine MPI_Errhandler_set may be used but its use is deprecated 🙈. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

• MPI_SUCCESS — No error; MPI routine completed successfully. ate, no notes 👑
• MPI_ERR_SESSION — Invalid session handle 🚫
• MPI_ERR_OTHER — Other error; use MPI_Error_string to get more information about this error code.

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and that's the whole page, bestie — every flag, every handle, every caveat, all of it, no cap 🫶

sign-off szn: this gem is from the MPI manual, dated 4/10/2026, and it lives at MPI_Session_set_errhandler(3) — so if you ever need it again, that's where you'll find it 💖✨🎀