Java8 helps a lot - CompletableFutures can be easier to reason about IMO. If you need to share state, you can use Akka to encapsulate the state in an actor, and

Java8 helps a lot - CompletableFutures can be easier to reason about IMO. If you need to share state, you can use Akka to encapsulate the state in an actor, and thus you will have (what appears to be) lock free concurrency!