Nothing implies that green threads need to run on a single core. The summary in your own link is pretty good: "In computer programming, a green thread (virtual

Nothing implies that green threads need to run on a single core. The summary in your own link is pretty good: "In computer programming, a green thread (virtual thread) is a thread that is scheduled by a runtime library or virtual machine (VM) instead of natively by the underlying operating system (OS)." Which is half of what we're looking for here. A thread that can be managed by the runtime, scheduled onto a native OS thread, and (here's the important part, where Common Lisp falls down on the job), transparently operates like a real thread or in other words, you can make normal blocking operations and the runtime just takes care of it. For example: goroutines