It's kinda tricky because when the stamp is generated we only provide a key and cannot know which store will use this key.

Key is flagged as non serializable for some store when calling aquire in the middleware

If we remove the Key and don't serialize it, the lock will never be released.
And we cannot easily check if the Store will prevent serializing the Key...

Do you have some idea/solution in mind ? @kbond

Does the key object need to be serialized? Can we just serialize the resource string? I'm not super familiar with the lock component.

Serializing it is required, as this is what allows the messenger consumer to become the owner of the lock acquired in the process dispatching the stamped message. The Key instance is the owner of the lock.

Using another key for the same resource string has a totally different meaning. It would try to acquire a conflicting lock (which would fail to be acquired as the other one is not released)

See https://symfony.com/doc/current/components/lock.html#serializing-locks for the documentation about serializing locks.

It might be great to expose a method on lockFactory/store to know earlier that it's incompatible with serializer.

Seeing as it is (will be) documented as "only supporting serializable locks", I don't think there's anything to do here. It isn't a big anyway.