1. My One Slide

2. Seriously, though…

3. Preemptive threads… …are difficult to reason about. Cooperative threads… …might refuse to yield. Semi-cooperative threads… …offer the best of both worlds! The idea: –Compiler inserts guarded yield points –Runtime preempts by setting a flag –Loader can verify placement of yield points Applications: –Eliminate fine-grained locks (CCured, Java) –Can we design a thread system that uses only this mechanism for synchronization? Key principle: Compiler makes simplifying assumptions and tells runtime system!