explicitly 2 threaded multi ros2 simple

src/full_topology/src/simple.cpp

@@ -98,7 +98,7 @@ int main(int argc, char **argv)
   #ifdef MULTI_THREADED
     // Create a multi-threaded executor to handle all nodes
     std::cout << "multi threaded ros default" << std::endl;
-    rclcpp::executors::MultiThreadedExecutor executor;
+    rclcpp::executors::MultiThreadedExecutor executor{{}, 2};
   #else
     // Create a single-threaded executor to handle all nodes
     std::cout << "single threaded ros default" << std::endl;