MPI_SEND_INIT(3)

📦
version 5.0.10 · 7 versions
, in ubuntu stonking

💖 MPI_SEND_INIT — bestie edition 💖

okay so this is a page from the Open MPI manual, section 3 (the MPI_SEND_INIT(3) one, yes THAT one). it's about building a handle for a standard send. and literally it's so useful, i need you to lock in 🔒

✨ NAME ✨

MPI_Send_init — Builds a handle for a standard send.

like. that's the whole vibe. it makes the handle. the send happens later. iykyk 👑

🎀 SYNTAX 🎀

C Syntax

#include <mpi.h>

int MPI_Send_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_SEND_INIT(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST,
             IERROR)
     <type>  BUF(*)
     INTEGER REQUEST, COUNT, DATATYPE, DEST, TAG
     INTEGER COMM, REQUEST, IERROR

(no shade to the older form but it is the older form. we say that with love 🫶)

Fortran 2008 Syntax

USE mpi_f08
MPI_Send_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 🌸

stuff you hand over, bestie, and the function is obsessed with all of it:

  • buf — Initial address of send buffer (choice). it's giving "where the data lives" 📦
  • count — Number of elements to send (integer). yes, elements. not bytes. don't do bytes. 💀
  • datatype — Type of each element (handle).
  • dest — Rank of destination (integer). who's getting this 🎯
  • tag — Message tag (integer).
  • comm — Communicator (handle). the group chat this is going down in 🌈

💅 OUTPUT PARAMETERS 💅

stuff it hands back to you:

  • request — Communication request (handle). this is THE thing. guard it with your life ✨
  • ierror — Fortran only: Error status (integer).

🔥 DESCRIPTION 🔥

so what does it actually do. it creates a persistent communication request for a standard mode send operation, and it binds to that request all the arguments of a send operation. all of them. the whole roster. no cap.

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

periodt. that's the whole thing. build it once, start it as many times as you want. main character energy tbh 💜

💀 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. like, ALL of them. everybody's gone 😭
  • 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. fr fr. it might just be over. 🙈

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_Ssend_init
  • MPI_Rsend_init
  • MPI_Recv_init
  • MPI_Start
  • MPI_Startall
  • MPI_Request_free

2003-2026, The Open MPI Community

okay that's the whole page, you ate that 🍓💖 and for the record: this manual page is from Open MPI, section MPI_SEND_INIT(3), dated Sep 10, 2026 — go forth and send, bestie, you've got this ✨🧚‍♀️

📦 where this page comes from