Work Contracts - Rethinking Task Based Concurrency & Parallelism for Low Latency C++

on YouTube ↗01h 08m

" summary

Work Contracts replaces task queues with a compact, lock‑free (often wait‑free) signal tree that lets threads traverse different branches to claim work. Benchmarks run with up to 16 threads and 16k queued items show scaling at high contention (17 ns tasks) with roughly 40x faster throughput versus moodycamel and ~100x versus average MPMC queues, using about half the memory. Contracts hold logic (repeatable calls), offer single-threaded execution per contract, support async deterministic destruction, and pair naturally with SPSC data queues; the implementation is built and benchmarked, and the numbers are concrete.

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" chapters (39)

1. 0:00Introduction
2. 0:26Problems with task queues
3. 1:29Decoupling logic and data
4. 4:54Introduction to work contracts
5. 6:00Signal tree structure
6. 7:40Benchmark setup
7. 9:07Performance results
8. 13:06Low contention benchmark
9. 15:23Medium contention benchmark
10. 16:25High contention benchmark
11. 17:24Empty task benchmark
12. 18:15Signal tree advantages
13. 20:43Perfect binary tree
14. 21:49Setting a signal
15. 22:56Selecting a signal
16. 24:50Task selection bias
17. 26:40Task selection fairness
18. 27:48Prioritization mechanism
19. 28:34Prioritization summary
20. 29:32Work contract overview
21. 30:17Hello world example
22. 32:34State and destructors
23. 33:19Asynchronous destruction
24. 35:02Error handling
25. 35:38Repeatable invocation
26. 36:08Data handling
27. 38:38Single threaded guarantee
28. 39:43Token usage
29. 39:55Looping and destruction
30. 42:02Threading example
31. 42:21Parallel execution
32. 43:16Output mangling prevention
33. 43:37SPSC queue integration
34. 44:24SPSC queue example
35. 46:13Concurrency summary
36. 46:24Conclusion
37. 46:36Talk recap
38. 49:32Acknowledgments
39. 50:21Q&A

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