[staticassertion]

Java services have managed for a long time to do just fine. Usually you just have dedicated threadpools for those db/ whatever calls.

But yes, eventually, for very heavy cases (more than what I would call "high") you will want async/await.

[pjmlp]

Which can still be done via java.util.concurrent (Callable, Futures, Promises, Flow) until Project Loom arrives.