MPI_TYPE_DUP(3)

💖 MPI_TYPE_DUP 💖

hi bestie!! this is the Open MPI page for MPI_Type_dup — aka the little glow-up spell that duplicates a data type with associated key values. yes, the datatype gets a twin. iconic behavior fr fr. 🫶

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✨ SYNTAX ✨

🌸 C Syntax

#include <mpi.h>

int MPI_Type_dup(MPI_Datatype type, MPI_Datatype *newtype)

🌸 Fortran Syntax

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

🌸 Fortran 2008 Syntax

USE mpi_f08
MPI_Type_dup(oldtype, newtype, ierror)
     TYPE(MPI_Datatype), INTENT(IN) :: oldtype
     TYPE(MPI_Datatype), INTENT(OUT) :: newtype
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🎀 INPUT PARAMETER 🎀

• type — the data type you're handing over, as a handle. that's the one getting duplicated, no cap ✨

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🦋 OUTPUT PARAMETERS 🦋

• newtype — the copy of type, as a handle. your brand new baby datatype 💅
• ierror — Fortran only bestie: the error status, an integer. 👑

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🌈 DESCRIPTION 🌈

okay so MPI_Type_dup is a type constructor that duplicates the existing type, key values and all. for each key value, the respective copy callback function is the one that decides the attribute value associated with this key in the new communicator. and listen — one particular action a copy callback may take is to delete the attribute from the new data type. so it's not forced to copy, it's got options. main character energy.

it returns in newtype a new data type with exactly the same properties as type, plus any copied cached information. the new data type has identical upper bound and lower bound and yields the same net result when fully decoded with the functions described in Section 8.6 of the MPI-2 standard. and newtype has the same committed state as the old type. literally twins. 💖

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💜 NOTES 💜

note that it is not defined by the MPI standard what happens if the attribute copy callback invokes other MPI functions. 🙈

in Open MPI though, it is not valid for attribute copy callbacks (or any of their children) to add or delete attributes on the same object on which the attribute copy callback is being invoked. so like... don't do that. periodt.

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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) is 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. 🔥
• 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.

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. 😭

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.

See also:

• MPI_Type_create_keyval

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👑 Copyright 👑

2003-2026, The Open MPI Community

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and that's the whole page bestie!! this was written under the Open MPI manual, page MPI_TYPE_DUP(3), dated Sep 10, 2026. go forth and duplicate your datatypes, you absolute legend 💅✨🎀