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

@@ -1000,5 +1000,31 @@ def test_release_no_waiters(self):
         self.assertFalse(sem.locked())
 
 
+class LockLoopTests:
+    def setUp(self):
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+
+    def tearDown(self):
+        asyncio.set_event_loop(None)
+        self.loop.close()
+
+    def test_lock_loop_not_running(self):
+        with self.assertWarns(DeprecationWarning):
+            asyncio.Lock()
+
+    def test_event_loop_not_running(self):
+        with self.assertWarns(DeprecationWarning):
+            asyncio.Event()
+
+    def test_condition_loop_not_running(self):
+        with self.assertWarns(DeprecationWarning):
+            asyncio.Condition()
+
+    def test_semaphore_loop_not_running(self):
+        with self.assertWarns(DeprecationWarning):
+            asyncio.Semaphore()
+
+
 if __name__ == '__main__':
     unittest.main()

Lib/test/test_asyncio/test_queues.py

@@ -714,5 +714,19 @@ class PriorityQueueJoinTests(_QueueJoinTestMixin, _QueueTestBase):
     q_class = asyncio.PriorityQueue
 
 
+class QueueLoopTests:
+    def setUp(self):
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+
+    def tearDown(self):
+        asyncio.set_event_loop(None)
+        self.loop.close()
+
+    def test_queue_loop_not_running(self):
+        with self.assertWarns(DeprecationWarning):
+            asyncio.Queue()
+
+
 if __name__ == '__main__':
     unittest.main()

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.