May 20, 2025 · May 20, 2025
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
        ''')
        assert_python_ok("-c", script)

    @skip_unless_reliable_fork
    def test_native_id_after_fork(self):
        script = """if True:
            import threading
            import os
            from test import support

            parent_thread_native_id = threading.current_thread().native_id
            print(parent_thread_native_id, flush=True)
            assert parent_thread_native_id == threading.get_native_id()
            childpid = os.fork()
            if childpid == 0:
                print(threading.current_thread().native_id, flush=True)
                assert threading.current_thread().native_id == threading.get_native_id()
            else:
                try:
                    assert parent_thread_native_id == threading.current_thread().native_id
                    assert parent_thread_native_id == threading.get_native_id()
                finally:
                    support.wait_process(childpid, exitcode=0)
            """
        rc, out, err = assert_python_ok('-c', script)
        self.assertEqual(rc, 0)
        self.assertEqual(err, b"")
        native_ids = out.strip().splitlines()
        self.assertEqual(len(native_ids), 2)
        self.assertNotEqual(native_ids[0], native_ids[1])

 class ThreadJoinOnShutdown(BaseTestCase):

    def _run_and_join(self, script):
diff --git a/Lib/threading.py b/Lib/threading.py
            # This thread is alive.
            self._ident = new_ident
            assert self._os_thread_handle.ident == new_ident
            if _HAVE_THREAD_NATIVE_ID:
                self._set_native_id()
        else:
            # Otherwise, the thread is dead, Jim.  _PyThread_AfterFork()
            # already marked our handle done.
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-04-19-17-16-46.gh-issue-132542.7T_TY_.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-19-17-16-46.gh-issue-132542.7T_TY_.rst
 Update :attr:`Thread.native_id <threading.Thread.native_id>` after
 :manpage:`fork(2)` to ensure accuracy. Patch by Noam Cohen.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1352,6 +1352,34 @@ def do_flush(args, *kwargs):
		''')
		assert_python_ok("-c", script)

		@skip_unless_reliable_fork
		def test_native_id_after_fork(self):
		script = """if True:
		import threading
		import os
		from test import support

		parent_thread_native_id = threading.current_thread().native_id
		print(parent_thread_native_id, flush=True)
		assert parent_thread_native_id == threading.get_native_id()
		childpid = os.fork()
		if childpid == 0:
		print(threading.current_thread().native_id, flush=True)
		assert threading.current_thread().native_id == threading.get_native_id()
		else:
		try:
		assert parent_thread_native_id == threading.current_thread().native_id
		assert parent_thread_native_id == threading.get_native_id()
		finally:
		support.wait_process(childpid, exitcode=0)
		"""
		rc, out, err = assert_python_ok('-c', script)
		self.assertEqual(rc, 0)
		self.assertEqual(err, b"")
		native_ids = out.strip().splitlines()
		self.assertEqual(len(native_ids), 2)
		self.assertNotEqual(native_ids[0], native_ids[1])

		class ThreadJoinOnShutdown(BaseTestCase):

		def _run_and_join(self, script):
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -951,6 +951,8 @@ def _after_fork(self, new_ident=None):
		# This thread is alive.
		self._ident = new_ident
		assert self._os_thread_handle.ident == new_ident
		if _HAVE_THREAD_NATIVE_ID:
		self._set_native_id()
		else:
		# Otherwise, the thread is dead, Jim. _PyThread_AfterFork()
		# already marked our handle done.
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Update :attr:`Thread.native_id <threading.Thread.native_id>` after
		:manpage:`fork(2)` to ensure accuracy. Patch by Noam Cohen.