MPI_STATUS_SET_ELEMENTS_X(3)

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version 5.0.10 · 4 versions
, in ubuntu stonking

💖 MPI_STATUS_SET_ELEMENTS_X(3) 💖

okay bestie, welcome to the Open MPI manual, glow-up edition ✨ this one is all about MPI_Status_set_elements <#mpi-status-set-elements> and MPI_Status_set_elements_x — two little functions that poke at the opaque part of a status so that MPI_Get_elements <#mpi-get-elements> will hand you back the count you told it about. it's giving "trust me, the number's in there" 💅

🌸 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 tying the count to, bestie (status). it goes in, it comes out changed 💖

🎀 INPUT PARAMETERS 🎀

  • datatype — the data type that goes with your count (handle).
  • count — how many elements you wanna associate with that status (integer).

🦋 OUTPUT PARAMETER 🦋

  • ierror — Fortran only, babes: the error status (integer).

🌈 DESCRIPTION 🌈

MPI_Status_set_elements <#mpi-status-set-elements> reaches into the opaque part of status and quietly sets things up so that a call to MPI_Get_elements or MPI_Get_elements_x will return count. and MPI_Get_count? it'll return a compatible value too. no cap 👑

here's the tea though — a later 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 with the same type signature as the data-type argument you used in the call to MPI_Status_set_elements <#mpi-status-set-elements>.*

⭐ NOTES ⭐

listen up, bestie, this part is important 🙈

the users are advised not to reuse the status fields for values other than those for which they were intended. do that and you might get unexpected results when you use the status object. like, calling MPI_Get_elements <#mpi-get-elements> may cause an error if the value is out of range, or it may be impossible to detect such an error at all. 😭

if you've got info that doesn't logically belong in a status, the extra_state argument that comes with a generalized request is literally right there for you.

also — and this is the big one — modifying the values in a status that MPI set internally, like the one from MPI_Recv, may lead to unpredictable results and is strongly discouraged. don't do it. i'm begging. 💀

💜 ERRORS 💜

almost all MPI routines return an error value; C routines hand it back as the return result of the function, and Fortran routines put it in the last argument.

before that error value comes back, 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>/MPI_Init_thread <#mpi-init-thread>, after MPI_Finalize <#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 <#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>/MPI_Comm_spawn_multiple <#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.

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

  • MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. the drama, honestly 💀
  • 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 <#mpi-abort> was called on that communicator. if called on a window or file, it acts as if MPI_Abort <#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.
  • 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 <#mpi-comm-create-errhandler> then MPI_Comm_set_errhandler <#mpi-comm-set-errhandler>
  • MPI_File_create_errhandler <#mpi-file-create-errhandler> then MPI_File_set_errhandler <#mpi-file-set-errhandler>
  • MPI_Session_create_errhandler <#mpi-session-create-errhandler> then MPI_Session_set_errhandler <#mpi-session-set-errhandler> or at MPI_Session_init <#mpi-session-init>
  • MPI_Win_create_errhandler <#mpi-win-create-errhandler> then MPI_Win_set_errhandler <#mpi-win-set-errhandler>

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

see the MPI man page <#open-mpi> for a full list of MPI error codes <#open-mpi-errors>.

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

2003-2026, The Open MPI Community

and that's the whole page, bestie!! you ate that 🎀✨ version vibes from Sep 10, 2026, straight outta the Open MPI manuals — now go forth and set those elements 💅💖

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