MPI_INITIALIZED(3)

💖 NAME 💖

MPI_Initialized — checks whether the MPI world model has been initialized 💅. and yeah bestie, this is the MPI_INITIALIZED(3) page from the Open MPI manual, so you're literally in the right spot.

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✨ SYNTAX ✨

okay so here's how you call it, no cap:

🧁 C Syntax 🧁

#include <mpi.h>

int MPI_Initialized(int *flag)

🍓 Fortran Syntax 🍓

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_INITIALIZED(FLAG, IERROR)
     LOGICAL FLAG
     INTEGER IERROR

🦋 Fortran 2008 Syntax 🦋

USE mpi_f08
MPI_Initialized(flag, ierror)
     LOGICAL, INTENT(OUT) :: flag
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🎀 OUTPUT PARAMETERS 🎀

these are the outputs, bestie:

• flag: true if the MPI world model has been initialized, and false otherwise (logical).
• ierror: Fortran only: error status (integer).

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🌸 DESCRIPTION 🌸

okay so this routine is literally how you find out whether the MPI world model has been initialized. and there's a whole different routine — MPI_Finalized — that's used to indicate whether the MPI world model has been finalized. different vibe, different check 💅.

also bestie, check MPI-5.0:11.4.1 for a list of MPI functionality that is available (e.g., even when the MPI world model has not yet initialized or has already been finalized). iykyk.

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😭 ERRORS 😭

okay so here's the error tea ☕. 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.
• 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. periodt.

see the MPI man page for a full list of MPI error codes. and see the Error Handling section of the MPI-3.1 standard for more information.

🔗 SEE ALSO 🔗

• MPI_Init
• MPI_Init_thread
• MPI_Finalize
• MPI_Finalized
• MPI_Session_init
• MPI_Session_finalize

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👑 COPYRIGHT 👑

2003-2026, The Open MPI Community

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and that's the whole page, bestie 🫶. the footer says this is the Open MPI version, dated Sep 11, 2026, so yeah — iconic, slay, you're welcome 💅✨