gh-126353: remove implicit creation of loop from get_event_loop

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 @@ def get_event_loop(self):
 
         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 @@ def get_event_loop(self):
 
     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

Lib/test/test_asyncio/test_events.py

@@ -2701,37 +2701,6 @@ def test_event_loop_policy(self):
         self.assertRaises(NotImplementedError, policy.set_event_loop, object())
         self.assertRaises(NotImplementedError, policy.new_event_loop)
 
-    def test_get_event_loop(self):
-        policy = asyncio.DefaultEventLoopPolicy()
-        self.assertIsNone(policy._local._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)
-        self.assertIs(loop, policy.get_event_loop())
-        loop.close()
-
-    def test_get_event_loop_calls_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:
-                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()
-
     def test_get_event_loop_after_set_none(self):
         policy = asyncio.DefaultEventLoopPolicy()
         policy.set_event_loop(None)
@@ -2912,11 +2881,6 @@ def test_get_event_loop_returns_running_loop2(self):
             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()
 

Misc/NEWS.d/next/Library/2024-11-03-10-48-07.gh-issue-126353.ChDzot.rst

@@ -0,0 +1 @@
+:func:`asyncio.get_event_loop` now does not implicitly creates an event loop if not already created, instead it raises :exc:`RuntimeError`. Patch by Kumar Aditya.