From fe5a6ab7bea927e887b7b3c2d4e8fe8eac7106c3 Mon Sep 17 00:00:00 2001 From: Kumar Aditya Date: Mon, 4 Nov 2024 14:21:20 +0530 Subject: [PATCH] gh-126353: remove implicit creation of loop from `asyncio.get_event_loop` (#126354) Remove implicit creation of loop from `asyncio.get_event_loop`. This is a step forward of deprecating the policy system of asyncio. --- Doc/library/asyncio-eventloop.rst | 5 ++- Doc/library/asyncio-policy.rst | 8 ++--- Doc/whatsnew/3.14.rst | 5 +++ Lib/asyncio/events.py | 24 ------------- Lib/test/test_asyncio/test_events.py | 34 +++++-------------- Lib/test/test_asyncio/test_unix_events.py | 6 ++-- Lib/test/test_cmd_line.py | 2 +- ...-11-03-10-48-07.gh-issue-126353.ChDzot.rst | 2 ++ 8 files changed, 24 insertions(+), 62 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2024-11-03-10-48-07.gh-issue-126353.ChDzot.rst diff --git a/Doc/library/asyncio-eventloop.rst b/Doc/library/asyncio-eventloop.rst index 14fd153f640..3ace6eda4d7 100644 --- a/Doc/library/asyncio-eventloop.rst +++ b/Doc/library/asyncio-eventloop.rst @@ -59,9 +59,8 @@ an event loop: instead of using these lower level functions to manually create and close an event loop. - .. deprecated:: 3.12 - Deprecation warning is emitted if there is no current event loop. - In some future Python release this will become an error. + .. versionchanged:: 3.14 + Raises a :exc:`RuntimeError` if there is no current event loop. .. function:: set_event_loop(loop) diff --git a/Doc/library/asyncio-policy.rst b/Doc/library/asyncio-policy.rst index 837ccc66067..09b75762ff0 100644 --- a/Doc/library/asyncio-policy.rst +++ b/Doc/library/asyncio-policy.rst @@ -97,11 +97,9 @@ asyncio ships with the following built-in policies: On Windows, :class:`ProactorEventLoop` is now used by default. - .. deprecated:: 3.12 - The :meth:`get_event_loop` method of the default asyncio policy now emits - a :exc:`DeprecationWarning` if there is no current event loop set and it - decides to create one. - In some future Python release this will become an error. + .. versionchanged:: 3.14 + The :meth:`get_event_loop` method of the default asyncio policy now + raises a :exc:`RuntimeError` if there is no set event loop. .. class:: WindowsSelectorEventLoopPolicy diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst index 21bc289c2be..deee683d7b8 100644 --- a/Doc/whatsnew/3.14.rst +++ b/Doc/whatsnew/3.14.rst @@ -576,6 +576,11 @@ asyncio (Contributed by Kumar Aditya in :gh:`120804`.) +* Removed implicit creation of event loop by :func:`asyncio.get_event_loop`. + It now raises a :exc:`RuntimeError` if there is no current event loop. + (Contributed by Kumar Aditya in :gh:`126353`.) + + collections.abc --------------- diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py index b63fe6aa796..ca0a4f2fee5 100644 --- a/Lib/asyncio/events.py +++ b/Lib/asyncio/events.py @@ -668,7 +668,6 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy): class _Local(threading.local): _loop = None - _set_called = False def __init__(self): self._local = self._Local() @@ -678,28 +677,6 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy): Returns an instance of EventLoop or raises an exception. """ - if (self._local._loop is None and - not self._local._set_called and - threading.current_thread() is threading.main_thread()): - stacklevel = 2 - try: - f = sys._getframe(1) - except AttributeError: - pass - else: - # Move up the call stack so that the warning is attached - # to the line outside asyncio itself. - while f: - module = f.f_globals.get('__name__') - if not (module == 'asyncio' or module.startswith('asyncio.')): - break - f = f.f_back - stacklevel += 1 - import warnings - warnings.warn('There is no current event loop', - DeprecationWarning, stacklevel=stacklevel) - self.set_event_loop(self.new_event_loop()) - if self._local._loop is None: raise RuntimeError('There is no current event loop in thread %r.' % threading.current_thread().name) @@ -708,7 +685,6 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy): def set_event_loop(self, loop): """Set the event loop.""" - self._local._set_called = True if loop is not None and not isinstance(loop, AbstractEventLoop): raise TypeError(f"loop must be an instance of AbstractEventLoop or None, not '{type(loop).__name__}'") self._local._loop = loop diff --git a/Lib/test/test_asyncio/test_events.py b/Lib/test/test_asyncio/test_events.py index 4dcf9f0e403..2ab638dc527 100644 --- a/Lib/test/test_asyncio/test_events.py +++ b/Lib/test/test_asyncio/test_events.py @@ -2704,33 +2704,22 @@ class PolicyTests(unittest.TestCase): def test_get_event_loop(self): policy = asyncio.DefaultEventLoopPolicy() self.assertIsNone(policy._local._loop) - with self.assertWarns(DeprecationWarning) as cm: + + with self.assertRaises(RuntimeError): loop = policy.get_event_loop() - self.assertEqual(cm.filename, __file__) - self.assertIsInstance(loop, asyncio.AbstractEventLoop) + self.assertIsNone(policy._local._loop) - self.assertIs(policy._local._loop, loop) - self.assertIs(loop, policy.get_event_loop()) - loop.close() - - def test_get_event_loop_calls_set_event_loop(self): + def test_get_event_loop_does_not_call_set_event_loop(self): policy = asyncio.DefaultEventLoopPolicy() with mock.patch.object( policy, "set_event_loop", wraps=policy.set_event_loop) as m_set_event_loop: - with self.assertWarns(DeprecationWarning) as cm: + with self.assertRaises(RuntimeError): loop = policy.get_event_loop() - self.addCleanup(loop.close) - self.assertEqual(cm.filename, __file__) - # policy._local._loop must be set through .set_event_loop() - # (the unix DefaultEventLoopPolicy needs this call to attach - # the child watcher correctly) - m_set_event_loop.assert_called_with(loop) - - loop.close() + m_set_event_loop.assert_not_called() def test_get_event_loop_after_set_none(self): policy = asyncio.DefaultEventLoopPolicy() @@ -2912,17 +2901,12 @@ class GetEventLoopTestsMixin: loop = asyncio.new_event_loop() self.addCleanup(loop.close) - with self.assertWarns(DeprecationWarning) as cm: - loop2 = asyncio.get_event_loop() - self.addCleanup(loop2.close) - self.assertEqual(cm.filename, __file__) - asyncio.set_event_loop(None) with self.assertRaisesRegex(RuntimeError, 'no current'): asyncio.get_event_loop() - with self.assertRaisesRegex(RuntimeError, 'no running'): - asyncio.get_running_loop() - self.assertIs(asyncio._get_running_loop(), None) + asyncio.set_event_loop(None) + with self.assertRaisesRegex(RuntimeError, 'no current'): + asyncio.get_event_loop() async def func(): self.assertIs(asyncio.get_event_loop(), loop) diff --git a/Lib/test/test_asyncio/test_unix_events.py b/Lib/test/test_asyncio/test_unix_events.py index 9ae54b68870..021f45478d6 100644 --- a/Lib/test/test_asyncio/test_unix_events.py +++ b/Lib/test/test_asyncio/test_unix_events.py @@ -1195,8 +1195,7 @@ class TestFork(unittest.IsolatedAsyncioTestCase): if pid == 0: # child try: - with self.assertWarns(DeprecationWarning): - loop = asyncio.get_event_loop_policy().get_event_loop() + loop = asyncio.get_event_loop() os.write(w, b'LOOP:' + str(id(loop)).encode()) except RuntimeError: os.write(w, b'NO LOOP') @@ -1207,8 +1206,7 @@ class TestFork(unittest.IsolatedAsyncioTestCase): else: # parent result = os.read(r, 100) - self.assertEqual(result[:5], b'LOOP:', result) - self.assertNotEqual(int(result[5:]), id(loop)) + self.assertEqual(result, b'NO LOOP') wait_process(pid, exitcode=0) @hashlib_helper.requires_hashdigest('md5') diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py index 35725718152..eca9adf9a7d 100644 --- a/Lib/test/test_cmd_line.py +++ b/Lib/test/test_cmd_line.py @@ -924,7 +924,7 @@ class CmdLineTest(unittest.TestCase): self.assertEqual(proc.stderr, '') def test_python_asyncio_debug(self): - code = "import asyncio; print(asyncio.get_event_loop().get_debug())" + code = "import asyncio; print(asyncio.new_event_loop().get_debug())" rc, out, err = assert_python_ok('-c', code, PYTHONASYNCIODEBUG='1') self.assertIn(b'True', out) diff --git a/Misc/NEWS.d/next/Library/2024-11-03-10-48-07.gh-issue-126353.ChDzot.rst b/Misc/NEWS.d/next/Library/2024-11-03-10-48-07.gh-issue-126353.ChDzot.rst new file mode 100644 index 00000000000..16d508b7ec6 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-11-03-10-48-07.gh-issue-126353.ChDzot.rst @@ -0,0 +1,2 @@ +:func:`asyncio.get_event_loop` now does not implicitly creates an event loop. +It now raises a :exc:`RuntimeError` if there is no set event loop. Patch by Kumar Aditya.