bpo-38599: Deprecate creation of asyncio object when the loop is not running

Lib/asyncio/locks.py

@@ -85,6 +85,11 @@ def __init__(self, *, loop=None):
                           "and scheduled for removal in Python 3.10.",
                           DeprecationWarning, stacklevel=2)
 
+        if not self._loop.is_running():
+            warnings.warn("The creation of asyncio objects without a running "
+                          "event loop is deprecated as of Python 3.9.",
+                          DeprecationWarning, stacklevel=2)
+
     def __repr__(self):
         res = super().__repr__()
         extra = 'locked' if self._locked else 'unlocked'
@@ -181,6 +186,11 @@ def __init__(self, *, loop=None):
                           "and scheduled for removal in Python 3.10.",
                           DeprecationWarning, stacklevel=2)
 
+        if not self._loop.is_running():
+            warnings.warn("The creation of asyncio objects without a running "
+                          "event loop is deprecated as of Python 3.9.",
+                          DeprecationWarning, stacklevel=2)
+
     def __repr__(self):
         res = super().__repr__()
         extra = 'set' if self._value else 'unset'
@@ -248,6 +258,11 @@ def __init__(self, lock=None, *, loop=None):
                           "and scheduled for removal in Python 3.10.",
                           DeprecationWarning, stacklevel=2)
 
+        if not self._loop.is_running():
+            warnings.warn("The creation of asyncio objects without a running "
+                          "event loop is deprecated as of Python 3.9.",
+                          DeprecationWarning, stacklevel=2)
+
         if lock is None:
             lock = Lock(loop=loop)
         elif lock._loop is not self._loop:
@@ -379,6 +394,11 @@ def __init__(self, value=1, *, loop=None):
                           "and scheduled for removal in Python 3.10.",
                           DeprecationWarning, stacklevel=2)
 
+        if not self._loop.is_running():
+            warnings.warn("The creation of asyncio objects without a running "
+                          "event loop is deprecated as of Python 3.9.",
+                          DeprecationWarning, stacklevel=2)
+
     def __repr__(self):
         res = super().__repr__()
         extra = 'locked' if self.locked() else f'unlocked, value:{self._value}'

Lib/asyncio/queues.py

@@ -40,6 +40,11 @@ def __init__(self, maxsize=0, *, loop=None):
                           DeprecationWarning, stacklevel=2)
         self._maxsize = maxsize
 
+        if not self._loop.is_running():
+            warnings.warn("The creation of asyncio objects without a running "
+                          "event loop is deprecated as of Python 3.9.",
+                          DeprecationWarning, stacklevel=2)
+
         # Futures.
         self._getters = collections.deque()
         # Futures.

Lib/test/test_asyncio/test_locks.py

@@ -305,6 +305,12 @@ async def f():
 
         self.loop.run_until_complete(f())
 
+    def test_lock_loop_not_running(self):
+        loop = asyncio.new_event_loop()
+        loop.stop()
+        with self.assertWarns(DeprecationWarning):
+            q = asyncio.Lock(loop=loop)
+
 
 class EventTests(test_utils.TestCase):
 
@@ -439,6 +445,12 @@ async def c1(result):
         self.assertTrue(t.done())
         self.assertTrue(t.result())
 
+    def test_event_loop_not_running(self):
+        loop = asyncio.new_event_loop()
+        loop.stop()
+        with self.assertWarns(DeprecationWarning):
+            q = asyncio.Event(loop=loop)
+
 
 class ConditionTests(test_utils.TestCase):
 
@@ -803,6 +815,12 @@ async def task_timeout():
         with self.assertWarns(DeprecationWarning):
             loop.run_until_complete(task_timeout())
 
+    def test_condition_loop_not_running(self):
+        loop = asyncio.new_event_loop()
+        loop.stop()
+        with self.assertWarns(DeprecationWarning):
+            q = asyncio.Condition(loop=loop)
+
 
 class SemaphoreTests(test_utils.TestCase):
 
@@ -999,6 +1017,12 @@ def test_release_no_waiters(self):
         sem.release()
         self.assertFalse(sem.locked())
 
+    def test_semaphore_loop_not_running(self):
+        loop = asyncio.new_event_loop()
+        loop.stop()
+        with self.assertWarns(DeprecationWarning):
+            q = asyncio.Semaphore(loop=loop)
+
 
 if __name__ == '__main__':
     unittest.main()

Lib/test/test_asyncio/test_queues.py

@@ -162,6 +162,12 @@ async def test():
         loop.run_until_complete(test())
         self.assertAlmostEqual(0.02, loop.time())
 
+    def test_queue_loop_not_running(self):
+        loop = asyncio.new_event_loop()
+        loop.stop()
+        with self.assertWarns(DeprecationWarning):
+            q = asyncio.Queue(loop=loop)
+
 
 class QueueGetTests(_QueueTestBase):
 

Misc/NEWS.d/next/Library/2020-01-26-20-54-04.bpo-38599.0PObOD.rst

@@ -0,0 +1,2 @@
+Add Deprecation Warning message when an Queue and Locks objects are created
+and the loop is not running.