May 22, 2025 · May 9, 2025
diff --git a/Include/internal/pycore_crossinterp.h b/Include/internal/pycore_crossinterp.h
 PyAPI_FUNC(PyObject *) _PyXI_ApplyError(_PyXI_error *err);


 typedef struct xi_session _PyXI_session;
 typedef struct _sharedns _PyXI_namespace;

 PyAPI_FUNC(void) _PyXI_FreeNamespace(_PyXI_namespace *ns);
 PyAPI_FUNC(_PyXI_namespace *) _PyXI_NamespaceFromNames(PyObject *names);
 PyAPI_FUNC(int) _PyXI_FillNamespaceFromDict(
    _PyXI_namespace *ns,
    PyObject *nsobj,
    _PyXI_session *session);
 PyAPI_FUNC(int) _PyXI_ApplyNamespace(
    _PyXI_namespace *ns,
    PyObject *nsobj,
    PyObject *dflt);


 // A cross-interpreter session involves entering an interpreter
 //(_PyXI_Enter()), doing some work with it, and finally exiting
 // that interpreter(_PyXI_Exit()).
 //with_PyXI_Enter(), doing some work with it, and finally exiting
 // that interpreterwith_PyXI_Exit().
 //
 // At the boundaries of the session, both entering and exiting,
 // data may be exchanged between the previous interpreter and the
 // target one in a thread-safe way that does not violate the
 // isolation between interpreters.  This includes setting objects
 // in the target's __main__ module on the way in, and capturing
 // uncaught exceptions on the way out.
 struct xi_session {
    // Once a session has been entered, this is the tstate that was
    // current before the session.  If it is different from cur_tstate
    // then we must have switched interpreters.  Either way, this will
    // be the current tstate once we exit the session.
    PyThreadState *prev_tstate;
    // Once a session has been entered, this is the current tstate.
    // It must be current when the session exits.
    PyThreadState *init_tstate;
    // This is true if init_tstate needs cleanup during exit.
    int own_init_tstate;

    // This is true if, while entering the session, init_thread took
    // "ownership" of the interpreter's __main__ module.  This means
    // it is the only thread that is allowed to run code there.
    // (Caveat: for now, users may still run exec() against the
    // __main__ module's dict, though that isn't advisable.)
    int running;
    // This is a cached reference to the __dict__ of the entered
    // interpreter's __main__ module.  It is looked up when at the
    // beginning of the session as a convenience.
    PyObject *main_ns;

    // This is set if the interpreter is entered and raised an exception
    // that needs to be handled in some special way during exit.
    _PyXI_errcode *error_override;
    // This is set if exit captured an exception to propagate.
    _PyXI_error *error;

    // -- pre-allocated memory --
    _PyXI_error _error;
    _PyXI_errcode _error_override;
 };
 typedef struct xi_session _PyXI_session;

 PyAPI_FUNC(_PyXI_session *) _PyXI_NewSession(void);
 PyAPI_FUNC(void) _PyXI_FreeSession(_PyXI_session *);

 PyAPI_FUNC(int) _PyXI_Enter(
    _PyXI_session *session,
    PyInterpreterState *interp,
    PyObject *nsupdates);
 PyAPI_FUNC(void) _PyXI_Exit(_PyXI_session *session);

 PyAPI_FUNC(PyObject *) _PyXI_GetMainNamespace(_PyXI_session *);

 PyAPI_FUNC(PyObject *) _PyXI_ApplyCapturedException(_PyXI_session *session);
 PyAPI_FUNC(int) _PyXI_HasCapturedException(_PyXI_session *session);

diff --git a/Modules/_interpretersmodule.c b/Modules/_interpretersmodule.c
                    PyObject **p_excinfo)
 {
    assert(!_PyErr_Occurred(tstate));
    _PyXI_session session = {0};
    _PyXI_session *session = _PyXI_NewSession();
    if (session == NULL) {
        return -1;
    }

    // Prep and switch interpreters.
    if (_PyXI_Enter(&session, interp, shareables) < 0) {
    if (_PyXI_Enter(session, interp, shareables) < 0) {
        if (_PyErr_Occurred(tstate)) {
            // If an error occured at this step, it means that interp
            // was not prepared and switched.
            _PyXI_FreeSession(session);
            return -1;
        }
        // Now, apply the error from another interpreter:
        PyObject *excinfo =_PyXI_ApplyError(session.error);
        PyObject *excinfo =_PyXI_ApplyCapturedException(session);
        if (excinfo != NULL) {
            *p_excinfo = excinfo;
        }
        assert(PyErr_Occurred());
        _PyXI_FreeSession(session);
        return -1;
    }

    // Run the script.
    int res = _run_script(script, session.main_ns);
    int res = -1;
    PyObject *mainns = _PyXI_GetMainNamespace(session);
    if (mainns == NULL) {
        goto finally;
    }
    res = _run_script(script, mainns);

 finally:
    // Clean up and switch back.
    _PyXI_Exit(&session);
    _PyXI_Exit(session);

    // Propagate any exception out to the caller.
    assert(!PyErr_Occurred());
    if (res < 0) {
        PyObject *excinfo = _PyXI_ApplyCapturedException(&session);
        PyObject *excinfo = _PyXI_ApplyCapturedException(session);
        if (excinfo != NULL) {
            *p_excinfo = excinfo;
        }
    }
    else {
        assert(!_PyXI_HasCapturedException(&session));
        assert(!_PyXI_HasCapturedException(session));
    }

    _PyXI_FreeSession(session);
    return res;
 }

        }
    }

    _PyXI_session session = {0};
    _PyXI_session *session = _PyXI_NewSession();
    if (session == NULL) {
        return NULL;
    }

    // Prep and switch interpreters, including apply the updates.
    if (_PyXI_Enter(&session, interp, updates) < 0) {
    if (_PyXI_Enter(session, interp, updates) < 0) {
        if (!PyErr_Occurred()) {
            _PyXI_ApplyCapturedException(&session);
            _PyXI_ApplyCapturedException(session);
            assert(PyErr_Occurred());
        }
        else {
            assert(!_PyXI_HasCapturedException(&session));
            assert(!_PyXI_HasCapturedException(session));
        }
        _PyXI_FreeSession(session);
        return NULL;
    }

    // Clean up and switch back.
    _PyXI_Exit(&session);
    _PyXI_Exit(session);
    _PyXI_FreeSession(session);

    Py_RETURN_NONE;
 }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -335,71 +335,29 @@ typedef struct _sharedexception {
		PyAPI_FUNC(PyObject ) _PyXI_ApplyError(_PyXI_error err);


		typedef struct xi_session _PyXI_session;
		typedef struct _sharedns _PyXI_namespace;

		PyAPI_FUNC(void) _PyXI_FreeNamespace(_PyXI_namespace *ns);
		PyAPI_FUNC(_PyXI_namespace ) _PyXI_NamespaceFromNames(PyObject names);
		PyAPI_FUNC(int) _PyXI_FillNamespaceFromDict(
		_PyXI_namespace *ns,
		PyObject *nsobj,
		_PyXI_session *session);
		PyAPI_FUNC(int) _PyXI_ApplyNamespace(
		_PyXI_namespace *ns,
		PyObject *nsobj,
		PyObject *dflt);


		// A cross-interpreter session involves entering an interpreter
		//(_PyXI_Enter()), doing some work with it, and finally exiting
		// that interpreter(_PyXI_Exit()).
		//with_PyXI_Enter(), doing some work with it, and finally exiting
		// that interpreterwith_PyXI_Exit().
		//
		// At the boundaries of the session, both entering and exiting,
		// data may be exchanged between the previous interpreter and the
		// target one in a thread-safe way that does not violate the
		// isolation between interpreters. This includes setting objects
		// in the target's __main__ module on the way in, and capturing
		// uncaught exceptions on the way out.
		struct xi_session {
		// Once a session has been entered, this is the tstate that was
		// current before the session. If it is different from cur_tstate
		// then we must have switched interpreters. Either way, this will
		// be the current tstate once we exit the session.
		PyThreadState *prev_tstate;
		// Once a session has been entered, this is the current tstate.
		// It must be current when the session exits.
		PyThreadState *init_tstate;
		// This is true if init_tstate needs cleanup during exit.
		int own_init_tstate;

		// This is true if, while entering the session, init_thread took
		// "ownership" of the interpreter's __main__ module. This means
		// it is the only thread that is allowed to run code there.
		// (Caveat: for now, users may still run exec() against the
		// __main__ module's dict, though that isn't advisable.)
		int running;
		// This is a cached reference to the __dict__ of the entered
		// interpreter's __main__ module. It is looked up when at the
		// beginning of the session as a convenience.
		PyObject *main_ns;

		// This is set if the interpreter is entered and raised an exception
		// that needs to be handled in some special way during exit.
		_PyXI_errcode *error_override;
		// This is set if exit captured an exception to propagate.
		_PyXI_error *error;

		// -- pre-allocated memory --
		_PyXI_error _error;
		_PyXI_errcode _error_override;
		};
		typedef struct xi_session _PyXI_session;

		PyAPI_FUNC(_PyXI_session *) _PyXI_NewSession(void);
		PyAPI_FUNC(void) _PyXI_FreeSession(_PyXI_session *);

		PyAPI_FUNC(int) _PyXI_Enter(
		_PyXI_session *session,
		PyInterpreterState *interp,
		PyObject *nsupdates);
		PyAPI_FUNC(void) _PyXI_Exit(_PyXI_session *session);

		PyAPI_FUNC(PyObject ) _PyXI_GetMainNamespace(_PyXI_session );

		PyAPI_FUNC(PyObject ) _PyXI_ApplyCapturedException(_PyXI_session session);
		PyAPI_FUNC(int) _PyXI_HasCapturedException(_PyXI_session *session);

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -444,42 +444,54 @@ _exec_in_interpreter(PyThreadState tstate, PyInterpreterState interp,
		PyObject **p_excinfo)
		{
		assert(!_PyErr_Occurred(tstate));
		_PyXI_session session = {0};
		_PyXI_session *session = _PyXI_NewSession();
		if (session == NULL) {
		return -1;
		}

		// Prep and switch interpreters.
		if (_PyXI_Enter(&session, interp, shareables) < 0) {
		if (_PyXI_Enter(session, interp, shareables) < 0) {
		if (_PyErr_Occurred(tstate)) {
		// If an error occured at this step, it means that interp
		// was not prepared and switched.
		_PyXI_FreeSession(session);
		return -1;
		}
		// Now, apply the error from another interpreter:
		PyObject *excinfo =_PyXI_ApplyError(session.error);
		PyObject *excinfo =_PyXI_ApplyCapturedException(session);
		if (excinfo != NULL) {
		*p_excinfo = excinfo;
		}
		assert(PyErr_Occurred());
		_PyXI_FreeSession(session);
		return -1;
		}

		// Run the script.
		int res = _run_script(script, session.main_ns);
		int res = -1;
		PyObject *mainns = _PyXI_GetMainNamespace(session);
		if (mainns == NULL) {
		goto finally;
		}
		res = _run_script(script, mainns);

		finally:
		// Clean up and switch back.
		_PyXI_Exit(&session);
		_PyXI_Exit(session);

		// Propagate any exception out to the caller.
		assert(!PyErr_Occurred());
		if (res < 0) {
		PyObject *excinfo = _PyXI_ApplyCapturedException(&session);
		PyObject *excinfo = _PyXI_ApplyCapturedException(session);
		if (excinfo != NULL) {
		*p_excinfo = excinfo;
		}
		}
		else {
		assert(!_PyXI_HasCapturedException(&session));
		assert(!_PyXI_HasCapturedException(session));
		}

		_PyXI_FreeSession(session);
		return res;
		}

Expand DownExpand Up		@@ -824,22 +836,27 @@ interp_set___main___attrs(PyObject self, PyObject args, PyObject *kwargs)
		}
		}

		_PyXI_session session = {0};
		_PyXI_session *session = _PyXI_NewSession();
		if (session == NULL) {
		return NULL;
		}

		// Prep and switch interpreters, including apply the updates.
		if (_PyXI_Enter(&session, interp, updates) < 0) {
		if (_PyXI_Enter(session, interp, updates) < 0) {
		if (!PyErr_Occurred()) {
		_PyXI_ApplyCapturedException(&session);
		_PyXI_ApplyCapturedException(session);
		assert(PyErr_Occurred());
		}
		else {
		assert(!_PyXI_HasCapturedException(&session));
		assert(!_PyXI_HasCapturedException(session));
		}
		_PyXI_FreeSession(session);
		return NULL;
		}

		// Clean up and switch back.
		_PyXI_Exit(&session);
		_PyXI_Exit(session);
		_PyXI_FreeSession(session);

		Py_RETURN_NONE;
		}
Expand Down