MPI_Info_create_env(3)

💖 MPI_Info_create_env(3) — the manual page, but make it cute

okay bestie, gather round, because this one's a lil function from the MPI manual (that's the manual name, she's the MPI page, iconic) and she's here to hand you an info object stuffed with deets about your application. no cap. 🦋

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✨ NAME ✨

MPI_Info_create_env — Creates an info object containing information about the application 💅

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🌸 SYNOPSIS 🌸

int MPI_Info_create_env(int argc, char *argv[], MPI_Info *info)

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🎀 INPUT/OUTPUT PARAMETERS 🎀

• argc — argc (None) 🫶
• argv — argv (None) ✨

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👑 OUTPUT PARAMETERS 👑

• info — info object (handle) 💖

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💜 NOTES FOR C 💜

so here's the tea: MPI_Info_create_env accepts NULL as input parameters. yes literally NULL. and doing that impacts the returned value. not me warning you about consequences bestie 😭

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🌈 NOTES FOR FORTRAN 🌈

The Fortran binding for MPI_Info_create_env does not take argc and argv. periodt.

subroutine MPI_INFO_CREATE_ENV(info, ierr)
integer info, ierr

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🔥 THREAD AND INTERRUPT SAFETY 🔥

This routine is thread-safe. Translation: multiple threads can use it at the same time and nobody needs to bring their own thread locks. group-chat friendly fr fr. 🫶

BUT. she is not interrupt safe. and it's giving why though. Typically this happens because of memory allocation routines like malloc or other non-MPICH runtime routines that are themselves not interrupt-safe. so like, don't interrupt her mid-malloc, ok? 💀

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🧚 NOTES FOR FORTRAN (yes, again 🧚)

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. no float, no vibes-only, just INTEGER. ✨

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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 (dramatic much? but true, she's serious). 😭

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 (old news, we don't do that anymore bestie). 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. she tries her best. 🥺

• MPI_SUCCESS — No error; MPI routine completed successfully. ate and left no crumbs. 👑
• MPI_ERR_ARG — Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK). 🚩
• MPI_ERR_OTHER — Other error; use MPI_Error_string to get more information about this error code. the catch-all, the main character of error codes. 💅

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lowkey reminder: don't sleep on the NULL thing in NOTES FOR C. it's small but it changes the returned value. iykyk. 🫶

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and that's the whole page babes, every flag, every error, every ierr, all of it, no crumbs left behind. this was MPI_Info_create_env(3), dated 4/10/2026, and it's giving timeless. mwah, go write some threaded MPI code and slay. 💖✨🎀🦋🌸💅🫶