How to store user data for every WebSocket connection in Helidon SE4

Question

Task: There is a server implemented using the Helidon SE4. I need to store user data associated with each WebSocket connection on the server side.

Problem: Unlike Jakarta WebSockets, Helidon SE 4 does not provide any mechanisms for this. WsSession does not have methods like Session.getUserProperties(), and the class implementing WsListener is reused for all connections established.

What I tried to do: But each WebSocket connection is provided with its own unique virtual thread.

1. I tried using ThreadLocal to store user data. However, this leads to memory leaks because the client can close the connection without notifying the server. As a result, none of the WsListener methods will ever be called from the desired thread, making it impossible to call ThreadLocal.remove() from the desired thread.
2. I also tried using ConcurrentHashMap. But this caused performance problems because all threads responsible for the connection are forced to constantly wait for each other.

Answer 1

If you use WsRouting.Builder the endpoint method can take a supplier which is ran once per request to return a listener.