MPI_SSEND_INIT(3)

📦
version 5.0.10 · 7 versions
, in ubuntu stonking

✨ NAME ✨

MPI_Ssend_init — bestie, this one builds you a handle for a synchronous send. It's from the Open MPI manual, section 3, and it's lowkey iconic.

🌸 SYNTAX 🌸

💻 C Syntax

#include <mpi.h>

int MPI_Ssend_init(const void *buf, int count, MPI_Datatype datatype,
     int dest, int tag, MPI_Comm comm, MPI_Request *request)

🧚 Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_SSEND_INIT(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST,
             IERROR)
     <type>  BUF(*)
     INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR

🦋 Fortran 2008 Syntax

USE mpi_f08
MPI_Ssend_init(buf, count, datatype, dest, tag, comm, request, ierror)
     TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
     INTEGER, INTENT(IN) :: count, dest, tag
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     TYPE(MPI_Comm), INTENT(IN) :: comm
     TYPE(MPI_Request), INTENT(OUT) :: request
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

🎀 INPUT PARAMETERS 🎀

  • buf — initial address of the send buffer (choice). It's giving "here's my data, take it" 💖
  • count — number of elements to send (integer). Count them, bestie, every single one.
  • datatype — type of each element (handle). Gotta tell MPI what flavor of data this is.
  • dest — rank of destination (integer). Who's receiving this masterpiece?
  • tag — message tag (integer). Your little name-tag so the wrong message doesn't walk in.
  • comm — communicator (handle). The group chat everyone's in.

🫶 OUTPUT PARAMETERS 🫶

  • request — communication request (handle). This is your new baby, guard it with your life.
  • ierror — Fortran only: error status (integer).

👑 DESCRIPTION 👑

It creates a persistent communication object for a synchronous mode send operation, and binds to it all the arguments of a send operation. Like, every single arg gets locked in. No cap.

A communication (send or receive) that uses a persistent request is initiated by the function MPI_Start.

So real talk: this is the setup, not the send. Nothing actually goes anywhere until you MPI_Start. The way that this is basically a pre-loaded vibe you fire off later? Obsessed. 🔥

💀 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. Fr fr, check it.

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. Yeah, it's a whole chain of custody, bestie.

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

  • MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. Everyone's going down together, that's the vibe. 😭
  • 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. The polite 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… assume it can't. Plan accordingly. 💅

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_Bsend_init
  • MPI_Send_init
  • MPI_Rsend_init
  • MPI_Recv_init
  • MPI_Start
  • MPI_Startall
  • MPI_Ssend

2003-2026, The Open MPI Community.

And that's the whole page, bestie — that was Open MPI, page MPI_SSEND_INIT(3), dated Sep 10, 2026. Slay, go forth and send synchronously. 💅✨🦋

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