Trying to get the state of lifecycle listener hangs forever

[ros2]

Trying to get the state of lifecycle listener hangs forever

[mikaelarguedas]

Looking at that demo it looks like expected behavior.
The lifecycle_listener is not a lifecycle node, just a node:

demos/lifecycle/src/lifecycle_listener.cpp

Line 34 in c44e525

class LifecycleListener : public rclcpp::Node

So it doesnt have a get state service. So the call hangs forever.

What we can do about it:

• Modifiy ros2 service call to timeout rather than waiting for service forever
• Make it clear that the demo it just to show the use of a lifecycle talker and that the listener is NOT a lifecycle node
• something we suggested last release: get rid of lifecycle_service_client_py.py completely and make people use the ros2 service calls listed below

[Karsten1987]

Where it is indeed the expected behavior, I agree, it's certainly not user friendly. #214 introduces a call to wait_for_service which would eventually time out when the services are not available and thus cleanup nicely.