Plugins should be unsubscribed by the event handler after the task state is Stopped

[rashmigottipati]

Current behavior:
When a stop task request is processed by the scheduler, it immediately starts unsubscribing all dependencies (plugins) of this task. This results in the plugins being used by the current firing of the workflow being killed.

Desired behavior:
Plugins should be unsubscribed after the task state is changed to Stopped state. There is an intermediate state between firing and stopped (i.e. Stopping). When the task state is changed to stopping, we close the channel "killchan" and closing of this killchan is received in the spin go routine. Changing of task state from stopping to stopped takes place here. So, plugins should be unsubscribed:

• By the event handler in scheduler
• After task state is changed to stopped (meaning that the task is truly stopped and the workflow finished executing)