MPI_RSEND_INIT(3)

💌 MPI_RSEND_INIT — the Open MPI glow-up ✨

okay bestie, welcome to the MPI_RSEND_INIT(3) page from the Open MPI manual set. sit down, hydrate, we're building a ready send handle and it's gonna be adorable 🎀

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🌸 SYNTAX 🌸

C Syntax 💅

#include <mpi.h>

int MPI_Rsend_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_RSEND_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_Rsend_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

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💖 INPUT PARAMETERS 💖

• buf — initial address of the send buffer, a.k.a. choice, a.k.a. where your lil data lives 🫶
• count — how many elements you're sending (integer, bestie, keep it honest)
• datatype — type of each element (a handle)
• dest — rank of the destination (integer) — who's getting this gift 🎁
• tag — message tag (integer), your secret lil label
• comm — communicator (handle), the group chat this all happens in

💜 OUTPUT PARAMETERS 💜

• request — communication request (handle) 👑
• ierror — Fortran only: error status (integer)

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🌈 DESCRIPTION 🌈

So basically it creates a persistent communication object for a ready mode send operation, and then it binds to it all the arguments of a send operation. like, it memorizes your whole send vibe so you don't have to repeat yourself. iconic behaviour, honestly. 🧚

And a communication (send or receive) that uses a persistent request is initiated by the function MPI_Start <#mpi-start>. that's the little magic button. press it, slay. ⭐

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😭 ERRORS 😭

almost all MPI routines return an error value, no cap. C routines give it back as the return result of the function, and Fortran routines drop it in the last argument. fr fr.

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> / 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>. 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, and they are:

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. 💀 dramatic but valid.
• 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, 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, aborts only the local process.
• MPI_ERRORS_RETURN — returns an error code to the application. polite ✨

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. bestie. heads up. 🚨

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.

See also:

• MPI_Bsend_init <#mpi-bsend-init>
• MPI_Send_init <#mpi-send-init>
• MPI_Ssend_init <#mpi-ssend-init>
• MPI_Recv_init <#mpi-recv-init>
• MPI_Start <#mpi-start>
• MPI_Startall <#mpi-startall>
• MPI_Request_free <#mpi-request-free>

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👑 Copyright 👑

2003-2026, The Open MPI Community

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and that's the whole page, bestie!! 💅 big shoutout to the Open MPI girlies — this manual page is dated Sep 10, 2026, lives at MPI_RSEND_INIT(3), and was served to you fresh from the Open MPI source. go start that persistent request and slay. periodt. 🦋🌸💖