MPI_STATUS_SET_ELEMENTS_X(3)

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💅 MPI_STATUS_SET_ELEMENTS_X(3) — the Open MPI glow-up

okay so bestie, welcome to the MPI_Status_set_elements and MPI_Status_set_elements_x page from the Open MPI manuals 🫶 this is the one that lets you sneak a count into the opaque part of a status so that MPI_Get_elements can hand it back to you later. iconic behavior, no cap ✨

✨ NAME ✨

MPI_Status_set_elements, MPI_Status_set_elements_x — modifies the opaque part of status so MPI_Get_elements can return count. literally that's the whole gig 💅

🌸 SYNTAX 🌸

💖 C Syntax 💖

#include <mpi.h>

int MPI_Status_set_elements(MPI_Status *status, MPI_Datatype datatype, int count)
int MPI_Status_set_elements_x(MPI_Status *status, MPI_Datatype datatype, MPI_Count count)

🦋 Fortran Syntax 🦋

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_STATUS_SET_ELEMENTS(STATUS, DATATYPE, COUNT, IERROR)
     INTEGER STATUS(MPI_STATUS_SIZE), DATATYPE, COUNT, IERROR
MPI_STATUS_SET_ELEMENTS_X(STATUS, DATATYPE, COUNT, IERROR)
     INTEGER STATUS(MPI_STATUS_SIZE), DATATYPE
        INTEGER(KIND=MPI_COUNT_KIND) COUNT
        INTEGER IERROR

🎀 Fortran 2008 Syntax 🎀

USE mpi_f08
MPI_Status_set_elements(status, datatype, count, ierror)
     TYPE(MPI_Status), INTENT(INOUT) :: status
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     INTEGER, INTENT(IN) :: count
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_Status_set_elements_x(status, datatype, count, ierror)
     TYPE(MPI_Status), INTENT(INOUT) :: status
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     INTEGER(KIND = MPI_COUNT_KIND), INTENT(IN) :: count
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

🌈 INPUT/OUTPUT PARAMETER 🌈

  • status — the status you're associating with count, bestie (status). it goes in and comes out changed, main character energy honestly 👑

🍓 INPUT PARAMETERS 🍓

  • datatype — the data type associated with count (handle). yep, that one 🧚
  • count — number of elements to associate with status (integer). the whole point tbh ✨

🌟 OUTPUT PARAMETER 🌟

  • ierror — Fortran only: error status (integer). classic Fortran move 💀

👑 DESCRIPTION 👑

MPI_Status_set_elements modifies the opaque part of status so that a call to MPI_Get_elements or MPI_Get_elements_x will return count. and MPI_Get_count will return a compatible value, slay 💅

okay so here's the tea 🍵 — a subsequent call to MPI_Get_count(status, datatype, count), to MPI_Get_elements(status, datatype, count), or to MPI_Get_elements_x(status, datatype, count) must use a data-type argument that has the same type signature as the data-type argument that was used in the call to MPI_Status_set_elements.* — like, fr fr, don't mix and match, it's giving chaos 🌪️

🦄 NOTES 🦄

bestie, please don't reuse the status fields for values other than those for which they were intended 🙈 the docs are literally advising against it. doing so may lead to unexpected results when using the status object. for example, calling MPI_Get_elements may cause an error if the value is out of range, or it may be impossible to detect such an error 😭 so like... why risk it.

the extra_state argument provided with a generalized request can be used to return information that does not logically belong in status — that's the designated spot for your little extras, okay? 🎀

furthermore, modifying the values in a status set internally by MPI, such as MPI_Recv, may lead to unpredictable results and is strongly discouraged. like, highkey do not. 💀

💀 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. standard, iykyk ✨

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. okay that was a lot, but every word of it matters 🫶

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 but effective 💀
  • 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. so specific, we love a precise queen 👑
  • MPI_ERRORS_RETURN — returns an error code to the application. the chill one 🌸

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. so like, no promises bestie 😭

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. go read, it's giving study era 📚✨

that's the whole page, bestie!! this little gem is MPI_STATUS_SET_ELEMENTS_X(3) from the Open MPI manual, © 2003–2026, The Open MPI Community, dated Sep 11, 2026 — mwah, go forth and set those elements responsibly 💖✨🎀

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