MPI_Request_get_status_any(3)

💖 NAME 💖

okay bestie, say hi to MPI_Request_get_status_any — it's the nondestructive test for the completion of any of the requests. it peeks, it does not delete, it does not consume. it's giving ✨window shopping✨ energy.

(this one lives in section 3 of the MPI manual, so we're in the library-call girlies' territory, iykyk.)

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🌸 SYNOPSIS 🌸

int MPI_Request_get_status_any(int count, const MPI_Request array_of_requests[],
int *indx, int *flag, MPI_Status *status)

that's the whole vibe. one call, it looks at your whole little roster of requests and tells you if any of them finished 🫶

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🎀 INPUT PARAMETERS 🎀

• count — count (non-negative integer). it's how many requests you're bringing to the function. keep it non-negative, fr fr, negative counts are not the moment.
• array_of_requests — array of requests (handle). your whole squad of request handles, lined up in an array like the group chat members list.

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👑 OUTPUT PARAMETERS 👑

• indx — index of operation that completed or MPI_UNDEFINED if none completed (integer). so it's either "hey bestie, request #3 is done 💅" or MPI_UNDEFINED which is the polite way of saying nobody's finished yet 😭
• flag — true if one of the operations is complete (logical). the vibe check. your one-glance yes/no.
• status — status object (Status). the receipts, the lore, all the details about the operation that actually completed.

notice how this is the nondestructive one? it tells you what's done without marking it done. you still gotta clean up those requests yourself later. no skipping that. 🙈

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🦋 THREAD AND INTERRUPT SAFETY 🦋

good news first: this routine is thread-safe. that means it may be safely used by multiple threads without the need for any user-provided thread locks. multiple girls, one function, no drama. slay. ✨

but — and bestie I need you to hear me — the routine is not interrupt safe. typically, this is due to the use of memory allocation routines such as malloc or other non-MPICH runtime routines that are themselves not interrupt-safe. so like, interrupt it and things get messy. don't do it. 💀

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🌈 NOTES FOR FORTRAN 🌈

for my Fortran girlies, there's a little extra garnish:

• 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. so the return value moved house and now it lives at the end of your arg list. periodt.
• 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.

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🍓 ERRORS 🍓

okay so, error handling lore time, and it applies to like... everything:

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 (so, legacy behaviour, we don't gatekeep but we also don't recommend 💅). 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. 🫶

here's the error roster, aka the mood ring of return codes:

• MPI_SUCCESS — No error; MPI routine completed successfully. she ate, no notes. ✨
• MPI_ERR_ARG — Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK). vague, mysterious, unhelpful, iconic in the worst way 😭
• MPI_ERR_COUNT — Invalid count argument. Count arguments must be non-negative; a count of zero is often valid. so zero? fine. negative? absolutely not, bestie.
• MPI_ERR_REQUEST — Invalid MPI_Request. Either null or, in the case of a MPI_Start or MPI_Startall, not a persistent request. check your handles, they might be fake.
• MPI_ERR_OTHER — Other error; use MPI_Error_string to get more information about this error code. the catch-all. the "it's giving unknown". go ask MPI_Error_string for the details 🔥

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and that's the whole page, bestie! go forth, peek at your requests non-destructively, and remember: thread-safe yes, interrupt-safe no, deprecated error handlers stay in the past 👑

mwah 💋 — this lil rewrite dropped on 4/10/2026, sourced straight from the MPI manual, and it's all about MPI_Request_get_status_any(3).