Implementing Async MPMC Channel in Rust

Transcript

1. Implementing Async MPMC Channel in Rust Motoyuki Kimura 1
2. MPMC Channel? • Multi Producer Multi Consumer Channel • i.e. have multiple senders and multiple receivers 2 Sender Sender Sender Receiver Receiver
3. Channel Types • Bounded / Unbounded • Async / Sync • SPSC, MPSC, MPMC 3
4. Prior Art 4 kind bounded / unbounded sync / async std::mpmc mpmc, mpsc, etc both sync crossbeam mpmc, mpsc, etc both sync async_channel mpmc both async kanal mpmc both sync/async Go channel mpmc both async
5. How do channels work? 5
6. • Allocate a fixed length area Bounded 6 Sender Receiver
7. Bounded 7 AAA BBB CCC Sender Receiver sender.send(CCC)
8. Bounded 8 BBB CCC Sender AAA Receiver
9. Bounded 9 HHH DDD EEE FFF GGG Sender CCC Receiver
10. Bounded 10 Sender Receiver • If there is no available data, reader would block Block!
11. Bounded 11 HHH III CCC DDD EEE FFF GGG Sender Receiver • If receiver is too slow, sender would block Block!
12. Bounded 12 HHH DDD EEE FFF GGG Sender Sender Sender Receiver Receiver • Actually, multiple senders and receivers work concurrently
13. Implementation Details 13
14. How to achieve block/unblock? 14
15. Block / Unblock 15 • Sync channel ◦ thread api (park, unpark) • Async channel ◦ waker api
16. Block / Unblock 16 Sender Receiver Block!
17. Block / Unblock 17 Sender Receiver Waker Waker list • When block happens, store waker somewhere
18. Block / Unblock 18 CCC Sender Receiver Waker1 Waker list • When block happens, store waker somewhere Pop from list
19. Depth of Wakerlist … 🚀 19 • For wakerlist, intrusive linked list would be much performant ◦ What are intrusive linked lists? ◦ new internal semaphore based on intrusive lists
20. How to test concurrent code base? 20
21. How to test concurrent code base? 21 • Multi threaded • Complex synchronization • Atomic Operations
22. How to test concurrent code base? 22
23. How to test concurrent code base? 23 Detect Deadlocks! 🙌
24. About Loom internals … 24 Video 🎥: https://youtu.be/-MRCgyiCxWU?si=a4NNwSxVgke6AFwZ Slide 📝: https://speakerdeck.com/kimuramotoyuki/bug-free-concurrency-in-rust
25. 25 https://crates.io/crates/chunnel
26. Thank you! 26