MPI_TYPE_DELETE_ATTR(3)

💖 MPI_Type_delete_attr 💖

okay bestie, we're in the Open MPI manual, page MPI_TYPE_DELETE_ATTR(3), and today's main character is a little function that deletes a datatype-caching attribute value associated with a key. sounds niche? it's giving niche. it's also giving necessary. let's get into it 🫶

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✨ NAME ✨

MPI_Type_delete_attr — deletes a datatype-caching attribute value associated with a key</p>. that's the whole job description, she's uncomplicated. 💅

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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 you're deleting the attribute from (it's a handle). bye bye lil attribute 🌈

📥 INPUT PARAMETER

• type_keyval — the key value, an integer. iykyk 🔑

📤 OUTPUT PARAMETER

• ierror — Fortran only: error status (integer). Fortran girlies get a whole extra slot for the tea 😭

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🦋 DESCRIPTION

MPI_Type_delete_attr deletes a datatype-caching attribute value that's associated with a key. simple as.

and here's the lore: this routine partially replaces MPI_Attr_delete, which is now deprecated. so if you're out here still calling the old one... no shade, but bestie, upgrade. she's retired. ⭐

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👑 NOTES

okay important, listen up, this is the part where you don't freestyle:

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

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 that the delete_fn callback is being invoked on. like... don't do that. please don't do that. it's giving chaos 💀

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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. classic Fortran behavior, always the last to speak 🙈

before that error value comes back to you, the current MPI error handler associated with the communication object (e.g., communicator, window, file) gets called. and 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. periodt.

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. and 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 the info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. 🌈

and 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. slay, consistent. 💅

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✨ the three predefined error handlers Open MPI ships with ✨

• 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 communication, 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, it 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, it aborts only the local process. flexible queen. 👑
• MPI_ERRORS_RETURN — returns an error code to the application. the chill one. the "talk to me" one. 🫶

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🎀 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

build your own, main character energy fr fr ✨

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note that MPI does not guarantee that an MPI program can continue past an error. so like... plan accordingly bestie 😭

see the MPI man page for a full list of MPI error codes.

see the Error Handling section of the MPI-3.1 standard for more information. 📚

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📜 Copyright

2003-2026, The Open MPI Community

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and that's a wrap on the MPI_TYPE_DELETE_ATTR(3) page from the Open MPI manual 💖 this one's dated Sep 10, 2026, and it's brought to you by The Open MPI Community — go forth, delete those attributes, and don't touch the same object from inside your delete_fn callback. love u, bye 🦋✨🎀