Green threads don't waste time on requests blocked on IO either. Both styles involve a software-level scheduler. The only difference between what most people call green threads and what most people call fibers is that one is preemptive and the other is cooperative. I actually prefer coding in the preemptive style.
I could be wrong, but it was my understanding that, on POSIX systems at least, the 1.8 MRI interpreter was smart enough to use non-blocking IO underneath the hood when performing IO calls and have a thread release its hold on the GIL when it is performing IO. That way, another thread could run while the first thread waits for an IO operation to complete. Either way, whether or not a software-level thread scheduler optimizes by using non-blocking IO or not is orthogonal to whether or not it schedules preemptively or cooperatively.
Sure node.js is asynchronous, fast, and fun to work with like rails. I downvoted you because your comment was nearly useless to someone who didn't already know what you were talking about. If you've got some advice, provide supporting information.
