But if you already have a runtime I don't know why it would be big deal to make them N:M threads as well. Makes managing CPU bound tasks easy as well as IO bound tasks.
- You are lazy and just don't care, let the runtime do it - Or you failed to realize that what you do could block
The first case is what annoys me. I think the developer should handle obvious cases manually. While the second case would be considered a bug in my model and the language should help you with that as explained earlier. If that works out, I mean to rule out mistakes for the second case, then this model is superior and more performant I think.