Preemptive scheduling, as opposed to cooperative scheduling.
Basically: the scheduler can interrupt an erlang thread at any time, instead of a depending on threads to cooperate with the scheduler to see if they should stop. In go, for example, goroutines will only check with the scheduler at function calls, selects, and a few other things like that.
I believe the BEAM only interrupts after "reduction" limit is reached, and is after function calls end. The big difference is that everything is a function call, so there's frequent opportunity to be interrupted. There's no functionless for-loop iteration, for example. I think having that would be a big sticking point for scheduling
Basically: the scheduler can interrupt an erlang thread at any time, instead of a depending on threads to cooperate with the scheduler to see if they should stop. In go, for example, goroutines will only check with the scheduler at function calls, selects, and a few other things like that.