MPI_TYPE_DELETE_ATTR(3)

💅 MPI_TYPE_DELETE_ATTR(3) — an Open MPI moment 🦋

okay bestie, so this is the Open MPI manual page for MPI_Type_delete_attr, and it's honestly giving "small function, big feelings." stay with me, it's not scary, i promise 🫶

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✨ NAME ✨

MPI_Type_delete_attr — deletes a datatype-caching attribute value associated with a key. literally that's the whole vibe: you got an attribute on a datatype, you got a key, and this function is the one that lets it go 💅

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🌸 SYNTAX 🌸

💖 C Syntax

#include <mpi.h>

int MPI_Type_delete_attr(MPI_Datatype type, int type_keyval)

💖 Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_DELETE_ATTR(TYPE, TYPE_KEYVAL, IERROR)
     INTEGER TYPE, TYPE_KEYVAL, IERROR

💖 Fortran 2008 Syntax

USE mpi_f08
MPI_Type_delete_attr(datatype, type_keyval, ierror)
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     INTEGER, INTENT(IN) :: type_keyval
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🎀 INPUT/OUTPUT PARAMETER 🎀

• type — the data type from which the attribute gets deleted (handle). (handle).n — yes that trailing n is really in there, we don't ask questions, we just respect the source 😭

🍓 INPUT PARAMETER 🍓

• type_keyval — the key value (integer). this is the key that says which attribute we're yeeting ✨

🌈 OUTPUT PARAMETER 🌈

• ierror — Fortran only: the error status (integer). classic Fortran, always putting it in the last argument 💜

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👑 DESCRIPTION 👑

MPI_Type_delete_attr deletes a datatype-caching attribute value associated with a key. that's the whole job, and it does it slayfully.

also, this routine partially replaces MPI_Attr_delete, which is now deprecated — so if you're still out here calling MPI_Attr_delete, bestie, it's time to move on, the new main character has arrived 💀

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🧚 NOTES 🧚

okay so here's the important caveat, and i need you to actually read it:

It is not defined by the MPI standard what happens if the delete_fn callback invokes other MPI functions. 🚨

and in Open MPI specifically: it is not valid for delete_fn callbacks (or any of their children) to add or delete attributes on the same object on which the delete_fn callback is being invoked. so like... don't do that. that's the rule. no cap 🙈

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💀 ERRORS 💀

almost all MPI routines return an error value — C routines as the return result of the function, and Fortran routines in the last argument.

before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) gets called. if no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. when MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. the initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. if no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

Open MPI includes three predefined error handlers that can be used:

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. dramatic? yes. effective? also yes 💅
• MPI_ERRORS_ABORT — an error handler that can be invoked on a communicator, window, file, or session. when called on a communicator, it acts as if MPI_Abort was called on that communicator. if called on a window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. if called on a session, aborts only the local process.
• MPI_ERRORS_RETURN — returns an error code to the application. chill, lowkey respectful 🫶

MPI applications can also implement their own error handlers by calling:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

Note that MPI does not guarantee that an MPI program can continue past an error. like, it might just be the end. 😭

see the MPI man page for a full list of MPI error codes. and see the Error Handling section of the MPI-3.1 standard for more information. iykyk 📚

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🎀 COPYRIGHT 🎀

2003-2026, The Open MPI Community

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and that's the page, bestie! ✨ this was brought to you by Open MPI, dated Sep 11, 2026, and the page itself is MPI_TYPE_DELETE_ATTR(3). go forth, delete those attributes, and remember: don't touch attributes on the same object from inside a delete_fn callback. mwah 💖🎀🦋