That's a good point, if you create only few green threads the overhead of dealing with them should nullify any advantage of lightweight scheduling and creating.

That's a good point, if you create only few green threads the overhead of dealing with them should nullify any advantage of lightweight scheduling and creating. Languages like Go like to advertise that you easily spawn millions of Green threads (which would fail with OS level threads or bring your OS down) but I've never seen a use case for that. For realistic applications a work stealing OS thread pool should be faster than spawning lots of green threads. But in the end, performance has to be measured, of course.