MPI_Status_set_source(3)

💖 NAME 💖

MPI_Status_set_source — bestie, it sets the MPI_SOURCE field in the status. that's the whole vibe. ✨

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✨ SYNOPSIS ✨

int MPI_Status_set_source(MPI_Status *status, int source)

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🌸 INPUT PARAMETERS 🌸

• source — the rank you want shoved into the MPI_SOURCE field (it's an integer, okay? like, a whole number bestie 💅)

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🦋 INPUT/OUTPUT PARAMETERS 🦋

• status — the status you're associating a tag with (of type Status, it's giving very in-out energy 🔄)

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🔥 THREAD AND INTERRUPT SAFETY 🔥

okay so this one is thread-safe, periodt. that means multiple threads can use this routine at the same time and you do not need to bring your own user-provided thread locks. no cap, it's genuinely fine. 🫶

but — and this is the plot twist 😭 — it is not interrupt safe. typically that's because of memory allocation routines like malloc, or other non-MPICH runtime routines that are themselves not interrupt-safe. so like, don't come for it about interrupts, that's just how it is. 💀

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🌈 NOTES FOR FORTRAN 🌈

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an extra argument called ierr chillin' at 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. (yes bestie, call. iconic behavior.)

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

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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 that value comes back to you, the current MPI error handler gets called. By default, this error handler aborts the MPI job. like, not me being dramatic, it literally ends the whole thing. 😭

You can change the error handler 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 maybe don't, bestie. 🙈

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. so, like, they're trying their best. 💖

• MPI_SUCCESS
  • No error; the MPI routine completed successfully. slay. ✨
• MPI_ERR_OTHER
  • Other error; use MPI_Error_string to get more information about this error code. go read the lore. 📖

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lowkey important reminder: this routine is thread-safe but not interrupt-safe, fr fr. don't skip that part. 🎀

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okay that's the whole page bestie, you ate that 🫶 this was MPI_Status_set_source(3), dated 4/10/2026, from the MPI manual — mwah, go forth and set those sources. 💅🌸✨