oslo messaging removed the blocking option

Use a threaded option with max size 1

Change-Id: I158fee200b828c4329af1b5e9cf2ef0c728ecf1d

devstack/plugin.sh

@@ -242,6 +242,8 @@ function configure_vitrage {
     elif is_service_enabled etcd3; then
         iniset $VITRAGE_CONF coordination backend_url "etcd3+http://${SERVICE_HOST}:$ETCD_PORT"
     fi
+
+    iniset $VITRAGE_CONF DEFAULT "executor_thread_pool_size" 1
 }
 
 # init_vitrage() - Initialize etc.

vitrage/messaging.py

@@ -60,8 +60,7 @@ def get_notification_listener(transport, targets, endpoints,
                               allow_requeue=False):
     """Return a configured oslo_messaging notification listener."""
     return oslo_msg.get_notification_listener(
-        transport, targets, endpoints, executor='blocking',
-        allow_requeue=allow_requeue)
+        transport, targets, endpoints, allow_requeue=allow_requeue)
 
 
 class VitrageNotifier(object):

vitrage/rpc.py

@@ -97,6 +97,5 @@ def get_server(target, endpoints, transport, serializer=None):
     return messaging.get_rpc_server(transport,
                                     target,
                                     endpoints,
-                                    executor='blocking',
                                     serializer=serializer,
                                     access_policy=access_policy)