Is there a good implementation of continuations in Java?
If so, what is the overhead like? The JVM wasn't designed with these sort of things in mind, right? So is this kind of going against the grain?
See Apache Javaflow http://commons.apache.org/sandbox/javaflow/
It's the only continuation package for java that's actively under development. The other one, RIFE, I'm not sure which state it's in.