MPI_Comm_detach_buffer(3)

✨ MPI_Comm_detach_buffer ✨

okay bestie, welcome to section 3 of the MPI manual, and today's main character is MPI_Comm_detach_buffer(3) 🫶

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💖 NAME 💖

MPI_Comm_detach_buffer — bestie, this one removes an existing buffer (the kind you'd use with MPI_Bsend and friends) from the communicator. that's it, that's the job 💅

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🌸 SYNOPSIS 🌸

int MPI_Comm_detach_buffer(MPI_Comm comm, void *buffer_addr, int *size)

int MPI_Comm_detach_buffer_c(MPI_Comm comm, void *buffer_addr, MPI_Count *size)

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🎀 INPUT PARAMETERS 🎀

• comm — the communicator (handle). it's giving "which little world are we doing this in" 🌈

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🦋 OUTPUT PARAMETERS 🦋

• buffer_addr — initial buffer address (choice). yeah we're handing it back to you, congrats 👑
• size — buffer size, in bytes (integer). the receipts, in bytes 🔥

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💜 NOTES FOR FORTRAN 💜

ngl this part matters so listen up 📣 all MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an additional argument ierr stuck on the end of the argument list. ierr is an integer and it means literally the same thing as the return value of the routine in C. and in Fortran, MPI routines are subroutines, so you invoke them with the call statement.

also: all MPI objects (like MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran. no cap 💫

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😭 ERRORS 😭

okay so every MPI routine (except MPI_Wtime and MPI_Wtick) returns an error value — C routines as the value of the function, Fortran routines in that last argument. and before the value is returned, the current MPI error handler is called. by default, this error handler aborts the MPI job 💀 so yeah, dramatic.

the error handler can 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 bestie, 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. so like… maybe it survives, maybe it doesn't 🤷‍♀️

the error codes themselves:

• MPI_SUCCESS — no error; MPI routine completed successfully. slay ✨
• MPI_ERR_ARG — invalid argument. some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK). rude but okay 💅
• MPI_ERR_COMM — invalid communicator. a common one is using a null communicator in a call (which is not even allowed in MPI_Comm_rank). not me forgetting to init 💀
• MPI_ERR_OTHER — other error; use MPI_Error_string to get more information about this error code. the catch-all, iykyk 🍓

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🧚 SEE ALSO 🧚

• MPI_Comm_attach_buffer
• MPI_Bsend

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and that's the whole vibe check, bestie 🌟 this has been MPI_Comm_detach_buffer(3) from the MPI manual, dated 4/10/2026 — go detach that buffer, you absolute icon 👑💖🦋