Actions (particularly ExecuteProcess) exist indefinitely

Bug report

Required Info:

• Operating System:
  • Ubuntu 20.04
• Installation type:
  • both
• Version or commit hash:
  • foxy
• DDS implementation:
  • fastrtps
• Client library (if applicable):
  • launch

Steps to reproduce issue

I have created a wrapper around the LaunchService which can dynamically add new Nodes and/or shutdown existing nodes.

New nodes are dynamically added by calling LaunchService.include_launch_description during runtime.

Nodes are stopped by emitting a ShutdownProcess event.

Expected behaviour

After ShutdownProcess, the node exits and the Node/ExecuteProcess object is destroyed.

Actual behavior

I observed that the Node (ExecuteProcess) object is not destroyed until the LaunchService completely shutdown. This is also the case if the node exits on it's own (without a ShutdownProcess event).

Additional information

The result is a small memory leak. Which stacks up in my use case of long lived LaunchService.

I looked at LaunchService._prune_and_count_entity_future_pairs where the Action is removed from entity_future_pairs. The Action is indeed pruned. However there are still ~18 references to it in event handlers.

Start at LaunchService._prune_and_count_entity_future_pairs and inspect the event-handler references that remain after an Action is removed from entity_future_pairs. Reproduce dynamic node shutdown and natural process exit in a long-lived LaunchService, then verify the Node or ExecuteProcess object can be released before the service itself shuts down.