Ah, the beauty of real-time Java is that it lets you mix hard real time code and soft- or non-realtime code in the same application, on different threads (and different classes).

Those classes designated as hard realtime will be compiled AOT, and will enjoy deterministic performance at the expense of sheer speed. Realtime threads are never preempted by JIT, or even by GC, as you run them within something similar to an arena memory region.

The idea is that only a small part of the application requires such hard deadline guarantees, and the rest should enjoy the full JVM treatment.