MPI_IMPROBE(3)

📦
version 5.0.11 · 16 versions
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💅 MPI_IMPROBE(3) — like, the Open MPI girlypop edition ✨

okay so bestie, welcome to MPI_IMPROBE from the Open MPI manual pages 🎀 this is a section 3 (library calls) page and honestly? she's kind of a big deal. Let's get into it 🦋

🌸 NAME 🌸

MPI_Improbe — non-blocking matched probe for a message. yes, non-blocking. she does NOT wait around for you, she's got main character energy 💅

✨ SYNTAX ✨

🌈 C Syntax 🌈

#include <mpi.h>

int MPI_Improbe(int source, int tag, MPI_Comm comm,
     int *flag, MPI_Message *message, MPI_Status *status)

🌈 Fortran Syntax 🌈

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_IMPROBE(SOURCE, TAG, COMM, FLAG, MESSAGE, STATUS, IERROR)
     LOGICAL FLAG
     INTEGER SOURCE, TAG, COMM, MESSAGE
     INTEGER STATUS(MPI_STATUS_SIZE), IERROR

🌈 Fortran 2008 Syntax 🌈

USE mpi_f08
MPI_Improbe(source, tag, comm, flag, message, status, ierror)
     INTEGER, INTENT(IN) :: source, tag
     TYPE(MPI_Comm), INTENT(IN) :: comm
     INTEGER, INTENT(OUT) :: flag
     TYPE(MPI_Message), INTENT(OUT) :: message
     TYPE(MPI_Status) :: status
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

🫶 INPUT PARAMETERS 🫶

  • source — source rank, or MPI_ANY_SOURCE if you're feeling ✨unbothered✨ (integer).
  • tag — the tag value, or MPI_ANY_TAG (integer). lowkey the message's vibes-label 🏷️
  • comm — the communicator (handle). the group chat this all happens in 💬

💖 OUTPUT PARAMETERS 💖

  • flag — flag (logical). it's giving yes/no energy 🚦
  • message — message (handle). the actual matched message, hold onto her 👑
  • status — status object (status). the receipts 📋
  • ierror — Fortran only: error status (integer). 🫡

🦋 DESCRIPTION 🦋

okay so like MPI_Probe and MPI_Iprobe, the MPI_Mprobe and MPI_Improbe operations let you query incoming messages without actually receiving them — except that MPI_Mprobe and MPI_Improbe give you a whole mechanism to receive the specific message that was matched, regardless of other intervening probe or receive operations 🎯 ngl that's the whole flex. This gives the application an opportunity to decide how to receive the message, based on the information returned by the probe. In particular, the application may allocate memory for the receive buffer according to the length of the probed message 📏 (iconic budgeting behavior, honestly).

A matching probe with MPI_PROC_NULL as source returns flag = true,

message = MPI_MESSAGE_NO_PROC, and the status object returns source ^ MPI_PROC_NULL, tag ^ MPI_ANY_TAG, and count ^ 0.

MPI_Iprobe returns a true value in flag if a message has been matched and can be received by passing the message handle to the MPI_Mrecv or MPI_Imrecv functions, provided the source was not MPI_PROC_NULL 💫

😭 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. no survivors, fr fr 💀
  • 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. she hands you the problem and minds her business 🎁

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. like, she might just not recover bestie, be aware 😭

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. iykyk 🧚

🔥 SEE ALSO 🔥

  • MPI_Mprobe
  • MPI_Probe
  • MPI_Iprobe
  • MPI_Mrecv
  • MPI_Imrecv
  • MPI_Cancel

2003-2026, The Open MPI Community 🫶

and that's the whole page bestie, slay 💅✨ Sep 11, 2026 — MPI_IMPROBE(3) — go forth and probe (non-blockingly) 🦋💖🎀

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