StateChangeListener being called after unsubscribing [concurrency]

[dlemures]

onStateChanged method from a StateChangeListener can be called after it has unsubscribe d.

Steps:

1. We have a Store S and Listener L.
2. In Thread 1, S starts notifying listeners using NotifySubscribersMiddleware .
3. CopyOnWriteArrayList is used to keep the listeners. Therefore, we iterate using a copy of the list that won't be changed during the iterator loop.
4. In Thread 2, L calls unsubscribe to unsubscribe from the Store S. This happens before step 3 is over and L is notified.
5. S notifies L calling onStateChanged, even thought it is already unsubscribed.

The scenario looks difficult to reproduce, however the consequences can be fatal.

[tmtron]

Is this the same as for Redux-store?

The subscriptions are snapshotted just before every dispatch() call. If you subscribe or unsubscribe while the listeners are being invoked, this will not have any effect on the dispatch() that is currently in progress. However, the next dispatch() call, whether nested or not, will use a more recent snapshot of the subscription list.

If so: how does Redux handle this issue? Or is it something that the users must just be aware of?