Goal:

The existing implementation of cancelling ongoing actions is poorly designed and implemented and has important implications from performance point of view.

Implementing an event-based approach requires more changes and the feasibility of cancelling an ongoing action is limited by the existing actionplan execution workflow and actions implementation of abort and revert. It also only applies to applier running in eventlet mode, it is not available in threading mode.

It has been decided to remove the current implementation. The behavior of Cancelling action-plans for actions will be to wait for the running task to complete and cancel all pending task

https://blueprints.launchpad.net/watcher/+spec/remove-cancel-ongoing-actions