Dealing With Contention hard
In non-blocking synchronization, what is the difference between 'Lock-Free' and 'Wait-Free'?
- A Lock-free uses locks.
- B Lock-Free guarantees system-wide progress (someone makes progress). Wait-Free guarantees per-thread progress (every thread makes progress in finite steps, strictly stronger).
- C Wait-free is slower.
- D They are synonymous.
Answer: B. Lock-Free guarantees system-wide progress (someone makes progress). Wait-Free guarantees per-thread progress (every thread makes progress in finite steps, strictly stronger).
Lock-free algorithms can still have starvation (one fast thread winning all CAS loops). Wait-free guarantees fairness and boundedness for everyone.
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