I was talking about scheduling in actor-pattern frameworks and non-OS runtime environments (JVM, C++, Python, etc. etc. etc.). Erlang's scheduler is preemptive

I was talking about scheduling in actor-pattern frameworks and non-OS runtime environments (JVM, C++, Python, etc. etc. etc.). Erlang's scheduler is preemptive. Erlang processes can be preempted by the scheduler in the middle of execution and moved to the back of the scheduler queue or to another scheduler thread. There is no requirement for a process itself to yield time back to the scheduler to make sure that other processes receive some execution time. This is one component of how it achieves "soft-realtime" semantics. Eight processes, on a system with 8 scheduler threads, running in a tight loop cannot cause all other processes in the Erlang VM to be blocked. Other processes will be given time. The only thing that violates this guarantee is long-running or blocking code executing on the native side of the NIF boundary. Akka, goroutines, Cloud Haskell, etc. are exactly the kinds of things I'm talking about when I say I don't understand the point of actor frameworks running in environments that can't preempt actor execution. You had better hope all your actor implementations are well-behaved or that the implementations you're going to import from someone else are all well behaved... otherwise you're going to lockup your scheduler's thread pool.