MPI_RECV_INIT(3)

📦
version 5.0.11 · 17 versions
, in arch rolling

💅 NAME

Okay bestie, welcome to the MPI_RECV_INIT(3) page in the Open MPI manual. This one is MPI_Recv_init — it builds you a handle for a receive. Slay.

🧾 SYNTAX

💖 C Syntax

#include <mpi.h>

int MPI_Recv_init(void *buf, int count, MPI_Datatype datatype,
     int source, int tag, MPI_Comm comm, MPI_Request *request)

🎀 Fortran Syntax

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

🦋 Fortran 2008 Syntax

USE mpi_f08
MPI_Recv_init(buf, count, datatype, source, tag, comm, request, ierror)
     TYPE(*), DIMENSION(..), ASYNCHRONOUS :: buf
     INTEGER, INTENT(IN) :: count, source, 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

  • count — the max number of elements you're receiving. It's an integer.
  • datatype — the type of each entry. It's a handle.
  • source — rank of the source. It's an integer.
  • tag — the message tag. It's an integer.
  • comm — the communicator. It's a handle.

🌸 INPUT/OUTPUT PARAMETER

  • buf — initial address of the receive buffer. The type is choice, iykyk.

🫶 OUTPUT PARAMETERS

  • request — the communication request. It's a handle.
  • ierror — Fortran only: error status. It's an integer.

✨ DESCRIPTION

Okay so MPI_Recv_init creates a persistent communication request for a receive operation. The argument buf is marked as OUT because you're literally giving permission to write on the receive buffer by passing that argument to MPI_Recv_init. Yes, that's the vibe.

A persistent communication request is inactive right after it's created — no active communication is attached to the request. Not me expecting it to do something immediately, bestie, because it does not.

A communication (send or receive) that uses a persistent request is initiated by the function MPI_Start or MPI_Startall. That's the main character energy right there.

💀 ERRORS

Almost all MPI routines return an error value; C routines return it as the return result of the function, and Fortran routines put it 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.
  • 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, it 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, it 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
Heads up, bestie: MPI does not guarantee that an MPI program can continue past an error.

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_Rsend_init
  • MPI_Send_init
  • MPI_Ssend_init
  • MPI_Start
  • MPI_Startall
  • MPI_Request_free

2003-2026, The Open MPI Community

okay that's the whole page, bestie! mwah 💋 — source/version: Open MPI; date: Sep 11, 2026; manual page: MPI_RECV_INIT(3). Bye 🫶✨

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