Adding comment about `del` about #17258

src/python/grpcio/grpc/_server.py

@@ -828,6 +828,8 @@ class _Server(grpc.Server):
         return _stop(self._state, grace)
 
     def __del__(self):
+        # TODO(lidiz): Depends on issue #17258 which is not solved yet
+        # The `_state` may not exist when object get deconstructed
         if hasattr(self, '_state'):
             _stop(self._state, None)
             del self._state