A couple of things of note: Run-to-completion scheduling is a thing in the real-time world. See for example Miro Samek's book Practical UML Statecharts in C++.

A couple of things of note: Run-to-completion scheduling is a thing in the real-time world. See for example Miro Samek's book Practical UML Statecharts in C++. XMOS makes real-time embedded CPUs supporting task-per-core architecture and hardware message passing. Commonly used in consumer real-time audio hardware, to pick one example. I believe some of the original Transputer people are involved.