No callbacks if client/server died

Bug report

Required Info:

• Operating System:
  • Ubuntu 22.04
• Installation type:
  • apt
• Version or commit hash:
  • iron
• DDS implementation:
  • Fast-RTPS
• Client library (if applicable):
  • rclcpp

Steps to reproduce issue

Start an action server

• action should be accepted, but not terminate

Start an action client that connects to the action server

Kill either the server or the client

Expected behavior

If the client is terminated, I would expect a CancelCallback.

If the server dies, I would expect ResultCallback for the goal with the status set to UNKNOWN

Actual behavior

No callbacks at all.

Additional information

I checked the API and could not find any way to check if a goal is still valid. On the server side the goal is still reported as active and executing if the client died.

Start with the rclcpp action server and action client entry points, then reproduce the reported sequence on Ubuntu 22.04: start both sides, accept a non-terminating action, and kill either process. Trace how client and server loss is detected and verify that the expected cancellation or UNKNOWN-result callback occurs.