# 17.2.322. MPI_Session_finalize

MPI_Session_finalize — releases all MPI state associated with a session

## 17.2.322.1. SYNTAX

### 17.2.322.1.1. C Syntax

    #include <mpi.h>

    int MPI_Session_finalize(MPI_Session *session)

### 17.2.322.1.2. Fortran Syntax

    USE MPI
    ! or the older form: INCLUDE 'mpif.h'

    MPI_SESSION_FINALIZE(SESSION, IERROR)
        INTEGER SESSION, IERROR

### 17.2.322.1.3. Fortran 2008 Syntax

    USE mpi_f08

    MPI_Session_finalize(session, ierror)
        TYPE(MPI_Session), INTENT(IN) :: session
        INTEGER, OPTIONAL, INTENT(OUT) :: ierror

## 17.2.322.2. INPUT PARAMETERS

- `session` : session to be finalized (handle)

## 17.2.322.3. OUTPUT PARAMETERS

- `ierror` : Fortran only: Error status (integer).

## 17.2.322.4. DESCRIPTION

MPI_Session_finalize releases all MPI state associated with the supplied session. Every instantiated session must be finalized using MPI_Session_finalize. The handle session is set to MPI_SESSION_NULL by the call.

## 17.2.322.5. NOTES

Before an MPI process invokes MPI_Session_finalize, the process must perform all MPI calls needed to complete its involvement in MPI communications: it must locally complete all MPI operations that it initiated and it must execute matching calls needed to complete MPI communications initiated by other processes. The call to MPI_Session_finalize does not free objects created by MPI calls; these objects are freed using MPI_XXX_FREE calls. MPI_Session_finalize may be synchronizing on any or all of the groups associated with communicators, windows, or files derived from the session and not disconnected, freed, or closed, respectively, before the call to MPI_Session_finalize procedure. MPI_Session_finalize behaves as if all such synchronizations occur concurrently. As MPI_Comm_free may mark a communicator for freeing later, MPI_Session_finalize may be synchronizing on the group associated with a communicator that is only freed (with MPI_Comm_free) rather than disconnected (with MPI_Comm_disconnect).

## 17.2.322.6. 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.

- `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.

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_Session_init