Fix for timeouting actions on run-action

Change-Id: I2aaed3c431134312942ab71ea8ad95f9b8529234
Partial-Bug: #1624284
(cherry picked from commit cca13bb3db)

mistral/cmd/launch.py

@@ -71,7 +71,7 @@ def launch_executor():
     executor_v2.register_membership()
 
     try:
-        executor_server.run()
+        executor_server.run(executor='threading')
     except (KeyboardInterrupt, SystemExit):
         pass
     finally:
@@ -100,6 +100,10 @@ def launch_engine():
     engine_v2.register_membership()
 
     try:
+        # Note(ddeja): Engine needs to be run in default (blocking) mode
+        # since using another mode may lead to deadlock.
+        # See https://review.openstack.org/#/c/356343/
+        # for more info.
         engine_server.run()
     except (KeyboardInterrupt, SystemExit):
         pass

mistral/engine/rpc_backend/base.py

@@ -70,7 +70,7 @@ class RPCServer(object):
         raise NotImplementedError
 
     @abc.abstractmethod
-    def run(self):
+    def run(self, executor='blocking'):
         """Runs the RPC server.
 
         """

mistral/engine/rpc_backend/kombu/kombu_server.py

@@ -54,7 +54,7 @@ class KombuRPCServer(rpc_base.RPCServer, kombu_base.Base):
         """Return whether server is running."""
         return self._running.is_set()
 
-    def run(self):
+    def run(self, executor='blocking'):
         """Start the server."""
         self.conn = self._make_connection(
             self.host,

mistral/engine/rpc_backend/oslo/oslo_server.py

@@ -38,7 +38,7 @@ class OsloRPCServer(rpc_base.RPCServer):
     def register_endpoint(self, endpoint):
         self.endpoints.append(endpoint)
 
-    def run(self):
+    def run(self, executor='blocking'):
         target = messaging.Target(
             topic=self.topic,
             server=self.server_id
@@ -48,7 +48,7 @@ class OsloRPCServer(rpc_base.RPCServer):
             rpc.get_transport(),
             target,
             self.endpoints,
-            executor='blocking',
+            executor=executor,
             serializer=ctx.RpcContextSerializer(ctx.JsonPayloadSerializer())
         )