MPIX_Stream_progress(3)

💖 NAME 💖

MPIX_Stream_progress — bestie, this one invokes progress on the given stream ✨

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🦋 SYNOPSIS 🦋

int MPIX_Stream_progress(MPIX_Stream stream)

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🎀 INPUT PARAMETERS 🎀

• stream — the stream object (it's a handle, okay, it's giving handle energy) 💅

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👑 THREAD AND INTERRUPT SAFETY 👑

So this routine is thread-safe, no cap. That means multiple threads can use it at the same time and you do not need to bring your own thread locks — the routine handles that for you. Slay.

But — and hear me out — it is not interrupt safe. 😭 Typically that's because it uses memory allocation routines like malloc, or other non-MPICH runtime routines that are themselves not interrupt-safe. So like, threads yes, interrupts no. Periodt.

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🧚 NOTES FOR FORTRAN 🧚

Every MPI routine in Fortran (except for MPI_WTIME and MPI_WTICK) has an extra argument called ierr tacked onto the end of the argument list. ierr is an integer and it means the exact same thing as the return value of the routine in C.

In Fortran, MPI routines are subroutines, and you invoke them with the call statement. That's just how it is, iykyk.

Also, all MPI objects (like MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran. Yes, all of them. 💜

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🌈 ERRORS 🌈

Every MPI routine (except MPI_Wtime and MPI_Wtick) returns an error value — for C routines it's the value of the function, and for Fortran routines it lives in that last argument. Before the value comes back to you, the current MPI error handler gets called.

⚠️ By default, this error handler aborts the MPI job. Like, whole thing, gone. 🙈

You can change the error handler though:

• MPI_Comm_set_errhandler — for communicators
• MPI_File_set_errhandler — for files
• MPI_Win_set_errhandler — for RMA windows

The MPI-1 routine MPI_Errhandler_set may also be used, but its use is deprecated (so don't come for me if you use the old one, bestie, it's giving legacy). The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned instead.

Note that MPI does not guarantee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible. Fingers crossed energy. 🫶

Here's what you might get back:

• MPI_SUCCESS — no error, the MPI routine completed successfully. Iconic. We love to see it. 💖
• MPI_ERR_OTHER — other error; use MPI_Error_string to get more information about this error code. So like, go read about it, k? 😭

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That's the whole page, babe. This gem lives in the MPI manual, this version is dated 4/10/2026, and yes, the page is literally called MPIX_Stream_progress(3). Go invoke some progress on that stream. 💅✨🌸