eliminate asyncio.sleep() and replace time.sleep() with a timeout (#2034)

Author: alexrudd2

pymodbus/server/async_io.py

@@ -4,7 +4,6 @@
 
 import asyncio
 import os
-import time
 import traceback
 from contextlib import suppress
 
@@ -578,10 +577,6 @@ async def async_stop(cls):
         if not cls.active_server:
             raise RuntimeError("ServerAsyncStop called without server task active.")
         await cls.active_server.server.shutdown()
-        if os.name == "nt":
-            await asyncio.sleep(1)
-        else:
-            await asyncio.sleep(0)
         cls.active_server = None
 
     @classmethod
@@ -593,11 +588,8 @@ def stop(cls):
         if not cls.active_server.loop.is_running():
             Log.info("ServerStop called with loop stopped.")
             return
-        asyncio.run_coroutine_threadsafe(cls.async_stop(), cls.active_server.loop)
-        if os.name == "nt":
-            time.sleep(10)
-        else:
-            time.sleep(0.1)
+        future = asyncio.run_coroutine_threadsafe(cls.async_stop(), cls.active_server.loop)
+        future.result(timeout=10 if os.name == 'nt' else 0.1)
 
 
 async def StartAsyncTcpServer(  # pylint: disable=invalid-name,dangerous-default-value