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[3.11] gh-93453: Only emit deprecation warning in asyncio.get_event_loop when a new event loop is created (#99949)

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It no longer emits a deprecation warning if the current event loop was set.

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
This commit is contained in:
Serhiy Storchaka 2022-12-06 17:15:44 +02:00 • committed by GitHub
parent 235f5fd2ca
commit 3fae04b10e
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13 changed files with 109 additions and 123 deletions
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22
Doc/library/asyncio-eventloop.rst
View file

@ -43,10 +43,12 @@ an event loop:
Get the current event loop.
If there is no current event loop set in the current OS thread,
the OS thread is main, and :func:`set_event_loop` has not yet
been called, asyncio will create a new event loop and set it as the
current one.
When called from a coroutine or a callback (e.g. scheduled with
call_soon or similar API), this function will always return the
running event loop.
If there is no running event loop set, the function will return
the result of ``get_event_loop_policy().get_event_loop()`` call.
Because this function has rather complex behavior (especially
when custom event loop policies are in use), using the
@ -58,10 +60,14 @@ an event loop:
event loop.
.. deprecated:: 3.10
Emits a deprecation warning if there is no running event loop.
In future Python releases, this function may become an alias of
:func:`get_running_loop` and will accordingly raise a
:exc:`RuntimeError` if there is no running event loop.
Deprecation warning is emitted if there is no current event loop.
In Python 3.12 it will be an error.
.. note::
In Python versions 3.10.0--3.10.8 and 3.11.0 this function
(and other functions which used it implicitly) emitted a
:exc:`DeprecationWarning` if there was no running event loop, even if
the current loop was set.
.. function:: set_event_loop(loop)

2
Doc/library/asyncio-llapi-index.rst
View file

@ -19,7 +19,7 @@ Obtaining the Event Loop
- The **preferred** function to get the running event loop.
* - :func:`asyncio.get_event_loop`
- Get an event loop instance (current or via the policy).
- Get an event loop instance (running or current via the current policy).
* - :func:`asyncio.set_event_loop`
- Set the event loop as current via the current policy.

5
Doc/library/asyncio-policy.rst
View file

@ -112,6 +112,11 @@ asyncio ships with the following built-in policies:
On Windows, :class:`ProactorEventLoop` is now used by default.
.. deprecated:: 3.11.1
:meth:`get_event_loop` now emits a :exc:`DeprecationWarning` if there
is no current event loop set and a new event loop has been implicitly
created. In Python 3.12 it will be an error.
.. class:: WindowsSelectorEventLoopPolicy

22
Lib/asyncio/events.py
View file

@ -671,6 +671,21 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy):
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:
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:
@ -786,12 +801,13 @@ def get_event_loop():
def _get_event_loop(stacklevel=3):
# This internal method is going away in Python 3.12, left here only for
# backwards compatibility with 3.10.0 - 3.10.8 and 3.11.0.
# Similarly, this method's C equivalent in _asyncio is going away as well.
# See GH-99949 for more details.
current_loop = _get_running_loop()
if current_loop is not None:
return current_loop
import warnings
warnings.warn('There is no current event loop',
DeprecationWarning, stacklevel=stacklevel)
return get_event_loop_policy().get_event_loop()

2
Lib/test/test_asyncio/test_base_events.py
View file

@ -746,7 +746,7 @@ class BaseEventLoopTests(test_utils.TestCase):
def test_env_var_debug(self):
code = '\n'.join((
'import asyncio',
'loop = asyncio.get_event_loop()',
'loop = asyncio.new_event_loop()',
'print(loop.get_debug())'))
# Test with -E to not fail if the unit test was run with

54
Lib/test/test_asyncio/test_events.py
View file

@ -2547,8 +2547,9 @@ class PolicyTests(unittest.TestCase):
def test_get_event_loop(self):
policy = asyncio.DefaultEventLoopPolicy()
self.assertIsNone(policy._local._loop)
loop = policy.get_event_loop()
with self.assertWarns(DeprecationWarning) as cm:
loop = policy.get_event_loop()
self.assertEqual(cm.filename, __file__)
self.assertIsInstance(loop, asyncio.AbstractEventLoop)
self.assertIs(policy._local._loop, loop)
@ -2562,7 +2563,10 @@ class PolicyTests(unittest.TestCase):
policy, "set_event_loop",
wraps=policy.set_event_loop) as m_set_event_loop:
loop = policy.get_event_loop()
with self.assertWarns(DeprecationWarning) as cm:
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
@ -2596,7 +2600,8 @@ class PolicyTests(unittest.TestCase):
def test_set_event_loop(self):
policy = asyncio.DefaultEventLoopPolicy()
old_loop = policy.get_event_loop()
old_loop = policy.new_event_loop()
policy.set_event_loop(old_loop)
self.assertRaises(TypeError, policy.set_event_loop, object())
@ -2709,15 +2714,11 @@ class GetEventLoopTestsMixin:
asyncio.set_event_loop_policy(Policy())
loop = asyncio.new_event_loop()
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(TestError):
asyncio.get_event_loop()
self.assertEqual(cm.filename, __file__)
with self.assertRaises(TestError):
asyncio.get_event_loop()
asyncio.set_event_loop(None)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(TestError):
asyncio.get_event_loop()
self.assertEqual(cm.filename, __file__)
with self.assertRaises(TestError):
asyncio.get_event_loop()
with self.assertRaisesRegex(RuntimeError, 'no running'):
asyncio.get_running_loop()
@ -2731,16 +2732,11 @@ class GetEventLoopTestsMixin:
loop.run_until_complete(func())
asyncio.set_event_loop(loop)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(TestError):
asyncio.get_event_loop()
self.assertEqual(cm.filename, __file__)
with self.assertRaises(TestError):
asyncio.get_event_loop()
asyncio.set_event_loop(None)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(TestError):
asyncio.get_event_loop()
self.assertEqual(cm.filename, __file__)
with self.assertRaises(TestError):
asyncio.get_event_loop()
finally:
asyncio.set_event_loop_policy(old_policy)
@ -2764,10 +2760,8 @@ class GetEventLoopTestsMixin:
self.addCleanup(loop2.close)
self.assertEqual(cm.filename, __file__)
asyncio.set_event_loop(None)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'no current'):
asyncio.get_event_loop()
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current'):
asyncio.get_event_loop()
with self.assertRaisesRegex(RuntimeError, 'no running'):
asyncio.get_running_loop()
@ -2781,15 +2775,11 @@ class GetEventLoopTestsMixin:
loop.run_until_complete(func())
asyncio.set_event_loop(loop)
with self.assertWarns(DeprecationWarning) as cm:
self.assertIs(asyncio.get_event_loop(), loop)
self.assertEqual(cm.filename, __file__)
self.assertIs(asyncio.get_event_loop(), loop)
asyncio.set_event_loop(None)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'no current'):
asyncio.get_event_loop()
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current'):
asyncio.get_event_loop()
finally:
asyncio.set_event_loop_policy(old_policy)

24
Lib/test/test_asyncio/test_futures.py
View file

@ -145,10 +145,8 @@ class BaseFutureTests:
self.assertTrue(f.cancelled())
def test_constructor_without_loop(self):
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'There is no current event loop'):
self._new_future()
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
self._new_future()
def test_constructor_use_running_loop(self):
async def test():
@ -158,12 +156,10 @@ class BaseFutureTests:
self.assertIs(f.get_loop(), self.loop)
def test_constructor_use_global_loop(self):
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
asyncio.set_event_loop(self.loop)
self.addCleanup(asyncio.set_event_loop, None)
with self.assertWarns(DeprecationWarning) as cm:
f = self._new_future()
self.assertEqual(cm.filename, __file__)
f = self._new_future()
self.assertIs(f._loop, self.loop)
self.assertIs(f.get_loop(), self.loop)
@ -499,10 +495,8 @@ class BaseFutureTests:
return (arg, threading.get_ident())
ex = concurrent.futures.ThreadPoolExecutor(1)
f1 = ex.submit(run, 'oi')
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(RuntimeError):
asyncio.wrap_future(f1)
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.wrap_future(f1)
ex.shutdown(wait=True)
def test_wrap_future_use_running_loop(self):
@ -517,16 +511,14 @@ class BaseFutureTests:
ex.shutdown(wait=True)
def test_wrap_future_use_global_loop(self):
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
asyncio.set_event_loop(self.loop)
self.addCleanup(asyncio.set_event_loop, None)
def run(arg):
return (arg, threading.get_ident())
ex = concurrent.futures.ThreadPoolExecutor(1)
f1 = ex.submit(run, 'oi')
with self.assertWarns(DeprecationWarning) as cm:
f2 = asyncio.wrap_future(f1)
self.assertEqual(cm.filename, __file__)
f2 = asyncio.wrap_future(f1)
self.assertIs(self.loop, f2._loop)
ex.shutdown(wait=True)

24
Lib/test/test_asyncio/test_streams.py
View file

@ -810,10 +810,8 @@ os.close(fd)
self.assertEqual(data, b'data')
def test_streamreader_constructor_without_loop(self):
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'There is no current event loop'):
asyncio.StreamReader()
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.StreamReader()
def test_streamreader_constructor_use_running_loop(self):
# asyncio issue #184: Ensure that StreamReaderProtocol constructor
@ -827,21 +825,17 @@ os.close(fd)
def test_streamreader_constructor_use_global_loop(self):
# asyncio issue #184: Ensure that StreamReaderProtocol constructor
# retrieves the current loop if the loop parameter is not set
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
self.addCleanup(asyncio.set_event_loop, None)
asyncio.set_event_loop(self.loop)
with self.assertWarns(DeprecationWarning) as cm:
reader = asyncio.StreamReader()
self.assertEqual(cm.filename, __file__)
reader = asyncio.StreamReader()
self.assertIs(reader._loop, self.loop)
def test_streamreaderprotocol_constructor_without_loop(self):
reader = mock.Mock()
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'There is no current event loop'):
asyncio.StreamReaderProtocol(reader)
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.StreamReaderProtocol(reader)
def test_streamreaderprotocol_constructor_use_running_loop(self):
# asyncio issue #184: Ensure that StreamReaderProtocol constructor
@ -855,13 +849,11 @@ os.close(fd)
def test_streamreaderprotocol_constructor_use_global_loop(self):
# asyncio issue #184: Ensure that StreamReaderProtocol constructor
# retrieves the current loop if the loop parameter is not set
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
self.addCleanup(asyncio.set_event_loop, None)
asyncio.set_event_loop(self.loop)
reader = mock.Mock()
with self.assertWarns(DeprecationWarning) as cm:
protocol = asyncio.StreamReaderProtocol(reader)
self.assertEqual(cm.filename, __file__)
protocol = asyncio.StreamReaderProtocol(reader)
self.assertIs(protocol._loop, self.loop)
def test_multiple_drain(self):

56
Lib/test/test_asyncio/test_tasks.py
View file

@ -200,10 +200,8 @@ class BaseTaskTests:
a = notmuch()
self.addCleanup(a.close)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'There is no current event loop'):
asyncio.ensure_future(a)
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.ensure_future(a)
async def test():
return asyncio.ensure_future(notmuch())
@ -213,12 +211,10 @@ class BaseTaskTests:
self.assertTrue(t.done())
self.assertEqual(t.result(), 'ok')
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
asyncio.set_event_loop(self.loop)
self.addCleanup(asyncio.set_event_loop, None)
with self.assertWarns(DeprecationWarning) as cm:
t = asyncio.ensure_future(notmuch())
self.assertEqual(cm.filename, __file__)
t = asyncio.ensure_future(notmuch())
self.assertIs(t._loop, self.loop)
self.loop.run_until_complete(t)
self.assertTrue(t.done())
@ -1536,10 +1532,8 @@ class BaseTaskTests:
self.addCleanup(a.close)
futs = asyncio.as_completed([a])
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'There is no current event loop'):
list(futs)
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
list(futs)
def test_as_completed_coroutine_use_running_loop(self):
loop = self.new_test_loop()
@ -1969,10 +1963,8 @@ class BaseTaskTests:
inner = coro()
self.addCleanup(inner.close)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaisesRegex(RuntimeError, 'There is no current event loop'):
asyncio.shield(inner)
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.shield(inner)
def test_shield_coroutine_use_running_loop(self):
async def coro():
@ -1986,15 +1978,13 @@ class BaseTaskTests:
self.assertEqual(res, 42)
def test_shield_coroutine_use_global_loop(self):
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
async def coro():
return 42
asyncio.set_event_loop(self.loop)
self.addCleanup(asyncio.set_event_loop, None)
with self.assertWarns(DeprecationWarning) as cm:
outer = asyncio.shield(coro())
self.assertEqual(cm.filename, __file__)
outer = asyncio.shield(coro())
self.assertEqual(outer._loop, self.loop)
res = self.loop.run_until_complete(outer)
self.assertEqual(res, 42)
@ -2820,7 +2810,7 @@ class BaseCurrentLoopTests:
self.assertIsNone(asyncio.current_task(loop=self.loop))
def test_current_task_no_running_loop_implicit(self):
with self.assertRaises(RuntimeError):
with self.assertRaisesRegex(RuntimeError, 'no running event loop'):
asyncio.current_task()
def test_current_task_with_implicit_loop(self):
@ -2984,10 +2974,8 @@ class FutureGatherTests(GatherTestsBase, test_utils.TestCase):
return asyncio.gather(*args, **kwargs)
def test_constructor_empty_sequence_without_loop(self):
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(RuntimeError):
asyncio.gather()
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.gather()
def test_constructor_empty_sequence_use_running_loop(self):
async def gather():
@ -3000,12 +2988,10 @@ class FutureGatherTests(GatherTestsBase, test_utils.TestCase):
self.assertEqual(fut.result(), [])
def test_constructor_empty_sequence_use_global_loop(self):
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
asyncio.set_event_loop(self.one_loop)
self.addCleanup(asyncio.set_event_loop, None)
with self.assertWarns(DeprecationWarning) as cm:
fut = asyncio.gather()
self.assertEqual(cm.filename, __file__)
fut = asyncio.gather()
self.assertIsInstance(fut, asyncio.Future)
self.assertIs(fut._loop, self.one_loop)
self._run_loop(self.one_loop)
@ -3093,10 +3079,8 @@ class CoroutineGatherTests(GatherTestsBase, test_utils.TestCase):
self.addCleanup(gen1.close)
gen2 = coro()
self.addCleanup(gen2.close)
with self.assertWarns(DeprecationWarning) as cm:
with self.assertRaises(RuntimeError):
asyncio.gather(gen1, gen2)
self.assertEqual(cm.filename, __file__)
with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
asyncio.gather(gen1, gen2)
def test_constructor_use_running_loop(self):
async def coro():
@ -3110,16 +3094,14 @@ class CoroutineGatherTests(GatherTestsBase, test_utils.TestCase):
self.one_loop.run_until_complete(fut)
def test_constructor_use_global_loop(self):
# Deprecated in 3.10
# Deprecated in 3.10, undeprecated in 3.11.1
async def coro():
return 'abc'
asyncio.set_event_loop(self.other_loop)
self.addCleanup(asyncio.set_event_loop, None)
gen1 = coro()
gen2 = coro()
with self.assertWarns(DeprecationWarning) as cm:
fut = asyncio.gather(gen1, gen2)
self.assertEqual(cm.filename, __file__)
fut = asyncio.gather(gen1, gen2)
self.assertIs(fut._loop, self.other_loop)
self.other_loop.run_until_complete(fut)

3
Lib/test/test_asyncio/test_unix_events.py
View file

@ -1740,7 +1740,8 @@ class PolicyTests(unittest.TestCase):
def test_child_watcher_replace_mainloop_existing(self):
policy = self.create_policy()
loop = policy.get_event_loop()
loop = policy.new_event_loop()
policy.set_event_loop(loop)
# Explicitly setup SafeChildWatcher,
# default ThreadedChildWatcher has no _loop property

3
Lib/test/test_coroutines.py
View file

@ -2411,7 +2411,8 @@ class UnawaitedWarningDuringShutdownTest(unittest.TestCase):
def test_unawaited_warning_during_shutdown(self):
code = ("import asyncio\n"
"async def f(): pass\n"
"asyncio.gather(f())\n")
"async def t(): asyncio.gather(f())\n"
"asyncio.run(t())\n")
assert_python_ok("-c", code)
code = ("import sys\n"

3
Misc/NEWS.d/next/Library/2022-12-02-13-05-00.gh-issue-93453.EFj1NN.rst Normal file
View file

@ -0,0 +1,3 @@
:func:`asyncio.get_event_loop` now only emits a deprecation warning when a
new event loop was created implicitly. It no longer emits a deprecation
warning if the current event loop was set.

12
Modules/_asynciomodule.c
View file

@ -339,13 +339,6 @@ get_event_loop(int stacklevel)
return loop;
}
if (PyErr_WarnEx(PyExc_DeprecationWarning,
"There is no current event loop",
stacklevel))
{
return NULL;
}
policy = PyObject_CallNoArgs(asyncio_get_event_loop_policy);
if (policy == NULL) {
return NULL;
@ -3129,6 +3122,11 @@ _asyncio_get_event_loop_impl(PyObject *module)
return get_event_loop(1);
}
// This internal method is going away in Python 3.12, left here only for
// backwards compatibility with 3.10.0 - 3.10.8 and 3.11.0.
// Similarly, this method's Python equivalent in asyncio.events is going
// away as well.
// See GH-99949 for more details.
/*[clinic input]
_asyncio._get_event_loop
stacklevel: int = 3