Remove __del__ from Redis (Fixes #1115)

CHANGES/1227.bugfix

@@ -0,0 +1 @@
+Change `__del__` in Redis to raise ResourceWarning (Fixes #1115)

aioredis/client.py

@@ -1054,14 +1054,23 @@ async def __aenter__(self: _RedisT) -> _RedisT:
     async def __aexit__(self, exc_type, exc_value, traceback):
         await self.close()
 
-    def __del__(self):
+    _DEL_MESSAGE = "Unclosed Redis client"
+
+    def __del__(self, _warnings: Any = warnings) -> None:
         try:
-            loop = asyncio.get_event_loop()
-            if loop.is_running():
-                loop.create_task(self.close())
-            else:
-                loop.run_until_complete(self.close())
-        except Exception:
+            if self.connection is not None:
+                _warnings.warn(
+                    f"Unclosed client session {self!r}",
+                    ResourceWarning,
+                    source=self,
+                )
+                context = {"client": self, "message": self._DEL_MESSAGE}
+                if self._source_traceback is not None:
+                    context["source_traceback"] = self._source_traceback
+                self._loop.call_exception_handler(context)
+        except AttributeError:
+            # loop was not initialized yet,
+            # either self._connector or self._loop doesn't exist
             pass
 
     async def close(self):
@@ -4349,16 +4358,7 @@ async def __aexit__(self, exc_type, exc_value, traceback):
     def __await__(self):
         return self._async_self().__await__()
 
-    def __del__(self):
-        try:
-            loop = asyncio.get_event_loop()
-            if loop.is_running():
-                loop.create_task(self.reset())
-            else:
-                loop.run_until_complete(self.reset())
-            super().__del__()
-        except Exception:
-            pass
+    _DEL_MESSAGE = "Unclosed Pipeline client"
 
     def __len__(self):
         return len(self.command_stack)