I still don't understand what's the correct way to replace thread locals holding initialization heavy & non thread-safe instances besides using a pool which pro

I still don't understand what's the correct way to replace thread locals holding initialization heavy & non thread-safe instances besides using a pool which produces a lot of overhead when using loom/virtual threads. In the past, with ThreadLocal, you'd have one instance per thread, making sure that those instances could only be used once and would only be instantiated for all threads of your (acceptor) thread pool Does anyone know the solution?