[hinkley]

IBM's early versions of the J9 compiler had a clever way of yielding (I assume you mean green thread yielding and not generator/closure yielding?)

Basically the thread scheduling system could trigger an overflow/underflow exception via a fairly fast operation by pushing an illegal value into a watchdog for the thread. An instruction was injected at the top of each function, loop, where the condition of the registers was in a knowable state, and I think a few other places to guarantee a degree of fairness.

For more realtime behavior you'd need to pepper these calls in many places, and any fusion operations would need to inject something similar into the instruction stream. Then you'd have to be very, very careful to avoid cache line aliasing that would crash the throughput via false sharing.