May 19, 2025 · May 19, 2025
diff --git a/Lib/test/test_interpreters/test_api.py b/Lib/test/test_interpreters/test_api.py
                    self.interp_exists(interpid))


    def test_remaining_threads(self):
        r_interp, w_interp = self.pipe()

        FINISHED = b'F'

        # It's unlikely, but technically speaking, it's possible
        # that the thread could've finished before interp.close() is
        # reached, so this test might not properly exercise the case.
        # However, it's quite unlikely and I'm too lazy to deal with it.
        interp = interpreters.create()
        interp.exec(f"""if True:
            import os
            import threading
            import time

            def task():
                time.sleep(1)
                os.write({w_interp}, {FINISHED!r})

            threads = [threading.Thread(target=task) for _ in range(3)]
            for t in threads:
                t.start()
            """)
        interp.close()

        self.assertEqual(os.read(r_interp, 1), FINISHED)

    def test_remaining_daemon_threads(self):
        interp = _interpreters.create(
            types.SimpleNamespace(
                use_main_obmalloc=False,
                allow_fork=False,
                allow_exec=False,
                allow_threads=True,
                allow_daemon_threads=True,
                check_multi_interp_extensions=True,
                gil='own',
            )
        )
        _interpreters.exec(interp, f"""if True:
            import threading
            import time

            def task():
                time.sleep(100)

            threads = [threading.Thread(target=task, daemon=True) for _ in range(3)]
            for t in threads:
                t.start()
            """)
        _interpreters.destroy(interp)


 class TestInterpreterPrepareMain(TestBase):

    def test_empty(self):
                spam.eggs()

            interp = interpreters.create()
            try:
                interp.exec(script)
            finally:
                interp.close()
            interp.exec(script)
            """)

        stdout, stderr = self.assert_python_failure(scriptfile)
        #      File "{interpreters.__file__}", line 179, in exec
        self.assertEqual(stderr, dedent(f"""\
            Traceback (most recent call last):
              File "{scriptfile}", line10, in <module>
              File "{scriptfile}", line9, in <module>
                interp.exec(script)
                ~~~~~~~~~~~^^^^^^^^
              {interpmod_line.strip()}
diff --git a/Lib/test/test_interpreters/test_lifecycle.py b/Lib/test/test_interpreters/test_lifecycle.py
                    'sub': sys.path[0],
                }}, indent=4), flush=True)
                """)
            interp.close()
            '''
        # <tmp>/
        #   pkg/
        argv = [sys.executable, '-c', '''if True:
            from test.support import interpreters
            interp = interpreters.create()
            try:
                raise Exception
            finally:
                interp.close()
            raise Exception
            ''']
        proc = subprocess.run(argv, capture_output=True, text=True)
        self.assertIn('Traceback', proc.stderr)
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py

            _testcapi.run_in_subinterp(%r)
            """ % (subinterp_code,)
        assert_python_ok("-c", script)
        with test.support.SuppressCrashReport():
            rc, out, err = assert_python_failure("-c", script)
        self.assertIn("Fatal Python error: Py_EndInterpreter: "
                      "not the last thread", err.decode())

    def _check_allowed(self, before_start='', *,
                       allowed=True,
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-01-08-12-52-47.gh-issue-128640.9nbh9z.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-01-08-12-52-47.gh-issue-128640.9nbh9z.rst
diff --git a/Programs/_testembed.c b/Programs/_testembed.c
    PySys_AddAuditHook(_audit_subinterpreter_hook, NULL);
    _testembed_initialize();

    PyThreadState *tstate = PyThreadState_Get();
    for (int i = 0; i < 3; ++i)
    {
        Py_EndInterpreter(Py_NewInterpreter());
        PyThreadState_Swap(tstate);
    }
    Py_NewInterpreter();
    Py_NewInterpreter();
    Py_NewInterpreter();

    Py_Finalize();

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
            }
            else {
                /* Fall back to the current tstate.  It's better than nothing. */
                // XXX No it's not
                main_tstate = tstate;
            }
        }

    _PyAtExit_Call(tstate->interp);

    /* Clean up any lingering subinterpreters.

       Two preconditions need to be met here:

        - This has to happen before _PyRuntimeState_SetFinalizing is
          called, or else threads might get prematurely blocked.
        - The world must not be stopped, as finalizers can run.
    */
    finalize_subinterpreters();

    assert(_PyThreadState_GET() == tstate);

    /* Copy the core config, PyInterpreterState_Delete() free
    _PyImport_FiniExternal(tstate->interp);
    finalize_modules(tstate);

    /* Clean up any lingering subinterpreters. */
    finalize_subinterpreters();

    /* Print debug stats if any */
    _PyEval_Fini();

    return tstate;
 }

 /* Delete an interpreter.  This requires that the given thread state
   is current, and that the thread has no remaining frames.
 /* Delete an interpreter and its last thread.  This requires that the
   given thread state is current, that the thread has no remaining
   frames, and that it is its interpreter's only remaining thread.
   It is a fatal error to violate these constraints.

   (Py_FinalizeEx() doesn't have these constraints -- it zaps
    _Py_FinishPendingCalls(tstate);

    _PyAtExit_Call(tstate->interp);
    _PyRuntimeState *runtime = interp->runtime;
    _PyEval_StopTheWorldAll(runtime);
    PyThreadState *list = _PyThreadState_RemoveExcept(tstate);

    if (tstate != interp->threads.head || tstate->next != NULL) {
        Py_FatalError("not the last thread");
    }

    /* Remaining daemon threads will automatically exit
       when they attempt to take the GIL (ex: PyEval_RestoreThread()). */
    _PyInterpreterState_SetFinalizing(interp, tstate);
    _PyEval_StartTheWorldAll(runtime);
    _PyThreadState_DeleteList(list, /*is_after_fork=*/0);

    // XXX Call something like _PyImport_Disable() here?

    PyInterpreterState *main_interp = _PyInterpreterState_Main();
    assert(final_tstate->interp == main_interp);
    _PyRuntimeState *runtime = main_interp->runtime;
    assert(!runtime->stoptheworld.world_stopped);
    assert(_PyRuntimeState_GetFinalizing(runtime) == NULL);
    struct pyinterpreters *interpreters = &runtime->interpreters;

    /* Get the first interpreter in the list. */

    /* Clean up all remaining subinterpreters. */
    while (interp != NULL) {
        /* Make a tstate for finalization. */
        PyThreadState *tstate = _PyThreadState_NewBound(interp, _PyThreadState_WHENCE_FINI);
        if (tstate == NULL) {
            // XXX Some graceful way to always get a thread state?
            Py_FatalError("thread state allocation failed");
        assert(!_PyInterpreterState_IsRunningMain(interp));

        /* Find the tstate to use for fini.  We assume the interpreter
           will have at most one tstate at this point. */
        PyThreadState *tstate = interp->threads.head;
        if (tstate != NULL) {
            /* Ideally we would be able to use tstate as-is, and rely
               on it being in a ready state: no exception set, not
               running anything (tstate->current_frame), matching the
               current thread ID (tstate->thread_id).  To play it safe,
               we always delete it and use a fresh tstate instead. */
            assert(tstate != final_tstate);
            _PyThreadState_Attach(tstate);
            PyThreadState_Clear(tstate);
            _PyThreadState_Detach(tstate);
            PyThreadState_Delete(tstate);
        }

        /* Enter the subinterpreter. */
        _PyThreadState_Attach(tstate);
        tstate = _PyThreadState_NewBound(interp, _PyThreadState_WHENCE_FINI);

        /* Destroy the subinterpreter. */
        _PyThreadState_Attach(tstate);
        Py_EndInterpreter(tstate);
        assert(_PyThreadState_GET() == NULL);
Original file line number	Diff line number	Diff line change
Expand Up		@@ -647,59 +647,6 @@ def test_created_with_capi(self):
		self.interp_exists(interpid))


		def test_remaining_threads(self):
		r_interp, w_interp = self.pipe()

		FINISHED = b'F'

		# It's unlikely, but technically speaking, it's possible
		# that the thread could've finished before interp.close() is
		# reached, so this test might not properly exercise the case.
		# However, it's quite unlikely and I'm too lazy to deal with it.
		interp = interpreters.create()
		interp.exec(f"""if True:
		import os
		import threading
		import time

		def task():
		time.sleep(1)
		os.write({w_interp}, {FINISHED!r})

		threads = [threading.Thread(target=task) for _ in range(3)]
		for t in threads:
		t.start()
		""")
		interp.close()

		self.assertEqual(os.read(r_interp, 1), FINISHED)

		def test_remaining_daemon_threads(self):
		interp = _interpreters.create(
		types.SimpleNamespace(
		use_main_obmalloc=False,
		allow_fork=False,
		allow_exec=False,
		allow_threads=True,
		allow_daemon_threads=True,
		check_multi_interp_extensions=True,
		gil='own',
		)
		)
		_interpreters.exec(interp, f"""if True:
		import threading
		import time

		def task():
		time.sleep(100)

		threads = [threading.Thread(target=task, daemon=True) for _ in range(3)]
		for t in threads:
		t.start()
		""")
		_interpreters.destroy(interp)


		class TestInterpreterPrepareMain(TestBase):

		def test_empty(self):
Expand DownExpand Up		@@ -808,10 +755,7 @@ def script():
		spam.eggs()

		interp = interpreters.create()
		try:
		interp.exec(script)
		finally:
		interp.close()
		interp.exec(script)
		""")

		stdout, stderr = self.assert_python_failure(scriptfile)
Expand All		@@ -820,7 +764,7 @@ def script():
		# File "{interpreters.__file__}", line 179, in exec
		self.assertEqual(stderr, dedent(f"""\
		Traceback (most recent call last):
		File "{scriptfile}", line10, in <module>
		File "{scriptfile}", line9, in <module>
		interp.exec(script)
		~~~~~~~~~~~^^^^^^^^
		{interpmod_line.strip()}
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -132,7 +132,6 @@ def test_sys_path_0(self):
		'sub': sys.path[0],
		}}, indent=4), flush=True)
		""")
		interp.close()
		'''
		# <tmp>/
		# pkg/
Expand DownExpand Up		@@ -173,10 +172,7 @@ def test_gh_109793(self):
		argv = [sys.executable, '-c', '''if True:
		from test.support import interpreters
		interp = interpreters.create()
		try:
		raise Exception
		finally:
		interp.close()
		raise Exception
		''']
		proc = subprocess.run(argv, capture_output=True, text=True)
		self.assertIn('Traceback', proc.stderr)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1689,7 +1689,10 @@ def f():

		_testcapi.run_in_subinterp(%r)
		""" % (subinterp_code,)
		assert_python_ok("-c", script)
		with test.support.SuppressCrashReport():
		rc, out, err = assert_python_failure("-c", script)
		self.assertIn("Fatal Python error: Py_EndInterpreter: "
		"not the last thread", err.decode())

		def _check_allowed(self, before_start='', *,
		allowed=True,
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1395,12 +1395,9 @@ static int test_audit_subinterpreter(void)
		PySys_AddAuditHook(_audit_subinterpreter_hook, NULL);
		_testembed_initialize();

		PyThreadState *tstate = PyThreadState_Get();
		for (int i = 0; i < 3; ++i)
		{
		Py_EndInterpreter(Py_NewInterpreter());
		PyThreadState_Swap(tstate);
		}
		Py_NewInterpreter();
		Py_NewInterpreter();
		Py_NewInterpreter();

		Py_Finalize();

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1992,7 +1992,6 @@ resolve_final_tstate(_PyRuntimeState *runtime)
		}
		else {
		/* Fall back to the current tstate. It's better than nothing. */
		// XXX No it's not
		main_tstate = tstate;
		}
		}
Expand DownExpand Up		@@ -2038,16 +2037,6 @@ _Py_Finalize(_PyRuntimeState *runtime)

		_PyAtExit_Call(tstate->interp);

		/* Clean up any lingering subinterpreters.

		Two preconditions need to be met here:

		- This has to happen before _PyRuntimeState_SetFinalizing is
		called, or else threads might get prematurely blocked.
		- The world must not be stopped, as finalizers can run.
		*/
		finalize_subinterpreters();

		assert(_PyThreadState_GET() == tstate);

		/* Copy the core config, PyInterpreterState_Delete() free
Expand DownExpand Up		@@ -2135,6 +2124,9 @@ _Py_Finalize(_PyRuntimeState *runtime)
		_PyImport_FiniExternal(tstate->interp);
		finalize_modules(tstate);

		/* Clean up any lingering subinterpreters. */
		finalize_subinterpreters();

		/* Print debug stats if any */
		_PyEval_Fini();

Expand DownExpand Up		@@ -2418,8 +2410,9 @@ Py_NewInterpreter(void)
		return tstate;
		}

		/* Delete an interpreter. This requires that the given thread state
		is current, and that the thread has no remaining frames.
		/* Delete an interpreter and its last thread. This requires that the
		given thread state is current, that the thread has no remaining
		frames, and that it is its interpreter's only remaining thread.
		It is a fatal error to violate these constraints.

		(Py_FinalizeEx() doesn't have these constraints -- it zaps
Expand DownExpand Up		@@ -2449,15 +2442,14 @@ Py_EndInterpreter(PyThreadState *tstate)
		_Py_FinishPendingCalls(tstate);

		_PyAtExit_Call(tstate->interp);
		_PyRuntimeState *runtime = interp->runtime;
		_PyEval_StopTheWorldAll(runtime);
		PyThreadState *list = _PyThreadState_RemoveExcept(tstate);

		if (tstate != interp->threads.head \|\| tstate->next != NULL) {
		Py_FatalError("not the last thread");
		}

		/* Remaining daemon threads will automatically exit
		when they attempt to take the GIL (ex: PyEval_RestoreThread()). */
		_PyInterpreterState_SetFinalizing(interp, tstate);
		_PyEval_StartTheWorldAll(runtime);
		_PyThreadState_DeleteList(list, /is_after_fork=/0);

		// XXX Call something like _PyImport_Disable() here?

Expand DownExpand Up		@@ -2488,8 +2480,6 @@ finalize_subinterpreters(void)
		PyInterpreterState *main_interp = _PyInterpreterState_Main();
		assert(final_tstate->interp == main_interp);
		_PyRuntimeState *runtime = main_interp->runtime;
		assert(!runtime->stoptheworld.world_stopped);
		assert(_PyRuntimeState_GetFinalizing(runtime) == NULL);
		struct pyinterpreters *interpreters = &runtime->interpreters;

		/* Get the first interpreter in the list. */
Expand DownExpand Up		@@ -2518,17 +2508,27 @@ finalize_subinterpreters(void)

		/* Clean up all remaining subinterpreters. */
		while (interp != NULL) {
		/* Make a tstate for finalization. */
		PyThreadState *tstate = _PyThreadState_NewBound(interp, _PyThreadState_WHENCE_FINI);
		if (tstate == NULL) {
		// XXX Some graceful way to always get a thread state?
		Py_FatalError("thread state allocation failed");
		assert(!_PyInterpreterState_IsRunningMain(interp));

		/* Find the tstate to use for fini. We assume the interpreter
		will have at most one tstate at this point. */
		PyThreadState *tstate = interp->threads.head;
		if (tstate != NULL) {
		/* Ideally we would be able to use tstate as-is, and rely
		on it being in a ready state: no exception set, not
		running anything (tstate->current_frame), matching the
		current thread ID (tstate->thread_id). To play it safe,
		we always delete it and use a fresh tstate instead. */
		assert(tstate != final_tstate);
		_PyThreadState_Attach(tstate);
		PyThreadState_Clear(tstate);
		_PyThreadState_Detach(tstate);
		PyThreadState_Delete(tstate);
		}

		/* Enter the subinterpreter. */
		_PyThreadState_Attach(tstate);
		tstate = _PyThreadState_NewBound(interp, _PyThreadState_WHENCE_FINI);

		/* Destroy the subinterpreter. */
		_PyThreadState_Attach(tstate);
		Py_EndInterpreter(tstate);
		assert(_PyThreadState_GET() == NULL);

Expand Down