Proactor policy fix (#17066)

* Proactor policy fix

* Backport Proactor policy for <py37

homeassistant/__main__.py

@@ -22,16 +22,30 @@ from homeassistant.const import (
 def set_loop() -> None:
     """Attempt to use uvloop."""
     import asyncio
+    from asyncio.events import BaseDefaultEventLoopPolicy
+
+    policy = None
 
     if sys.platform == 'win32':
-        asyncio.set_event_loop(asyncio.ProactorEventLoop())
+        if hasattr(asyncio, 'WindowsProactorEventLoopPolicy'):
+            policy = asyncio.WindowsProactorEventLoopPolicy()
+        else:
+            class ProactorPolicy(BaseDefaultEventLoopPolicy):
+                """Event loop policy to create proactor loops."""
+
+                _loop_factory = asyncio.ProactorEventLoop
+
+            policy = ProactorPolicy()
     else:
         try:
             import uvloop
         except ImportError:
             pass
         else:
-            asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
+            policy = uvloop.EventLoopPolicy()
+
+    if policy is not None:
+        asyncio.set_event_loop_policy(policy)
 
 
 def validate_python() -> None:

homeassistant/util/async_.py

@@ -2,7 +2,6 @@
 import concurrent.futures
 import threading
 import logging
-import sys
 from asyncio import coroutines
 from asyncio.events import AbstractEventLoop
 from asyncio.futures import Future
@@ -23,10 +22,7 @@ except AttributeError:
 
     def asyncio_run(main: Awaitable[_T], *, debug: bool = False) -> _T:
         """Minimal re-implementation of asyncio.run (since 3.7)."""
-        if sys.platform == 'win32':
+        loop = asyncio.new_event_loop()
-            loop = asyncio.ProactorEventLoop()
-        else:
-            loop = asyncio.new_event_loop()
         asyncio.set_event_loop(loop)
         loop.set_debug(debug)
         try: