[EdHominem]

I think it's not as much green threads as very many threads. And then they're not as much threads as independently threadable parts of the code.

You don't have to intentionally write a work queue and balance the number of readers vs writers, etc. You just let the runtime make things go as fast as possible.

They do get balanced across cores in almost all cases. Erlang is a functional language which really lends itself to this.