[krisdol]

Green threads were removed from ruby when 1.9 was released, and we're almost at 2.2 now. Is there some other factor limiting you to one core?

Edit: I just want to say I've done some more reading on the subject and have learned that the GIL does in fact prevent a single process from running on multiple cores. That said, if you wrote a thread-safe ruby application, then just fork it n-1 times (where n = number of cores) and everything should be fine.