Many languages offer threads, which either the operating system or the runtime will preëmpt to ensure they all make progress in some vaguely fair way no matter

Many languages offer threads, which either the operating system or the runtime will preëmpt to ensure they all make progress in some vaguely fair way no matter how they behave. I haven't been required to write "I have more work to do, but this would be a good place to interrupt me" for fifteen years (when Win95 displaced Win3).