Thread-Safety in Go - An Overlooked Concern

A talk on learning the fundamentals of thread-safety in Go as presented on The Go Conference, Japan (https://gocon.jp/)

Materials - http://bit.ly/goconjp-thread-safety

Transcript

1. Thread-Safety in Go An Overlooked Concern P. Mihaylov Software Engineer, Tech. Trainer, Speaker preslav@pmihaylov.com Go Conference Tokyo 2021, A random zoom room on the Internet
2. 👋 こんにちは
4. I like 󰞵ing & 󰳓ing
5. Check out my work @ github.com/preslavmihaylov, pmihaylov.com
6. Why not a talk on concurrency?
7. Most courses/books are incomplete…
8. Not enough ❤ for thread-safety
9. Concurrency without thread-safety -> 200 mp/h 🏎 without safety measures
10. Goals → 1) Learn the fundamentals 2) Get guidance on next steps
11. What’s covered 1. What does “thread-safety” mean? 2. Should you care about it at all? 3. Thread-safety problems & solutions a. When is there a potential thread-safety issue? b. Atomic access to shared state c. Delegating thread-safety d. Atomic compound actions e. Visibility & stale data 4. Where to go from here?
12. What does “thread-safety” mean?
13. Safe classes → behave correctly
14. Thread-safe classes → behave correctly while bombarded by a gazillion goroutines
15. Should you care about it at all?
16. “I don’t need thread-safe classes as I’m typically writing web apps without spawning any threads…” the average web dev
17. You’re already writing multi-threaded applications...
18. ...and no. Channels can’t save you every time
20. Thread-safety problems & solutions
21. When is there a potential thread-safety issue?
23. Is it thread-safe? Join at slido.com #gocon21s
27. Is it thread-safe? Join at slido.com #gocon21s
28. Shared mutable state
29. Non-shared state Stack #1 Thread #1 Non-shared state #1 Non-shared state #2 Shared memory aka heap Shared state Non-shared state Stack #2 Thread #2
30. Atomic access to shared state
33. What can go wrong?
35. Using Mutexes is Go’s standard way to add critical sections/locks
36. Delegating thread-safety
39. Delegated thread-safety → relying on the thread-safetiness of objects you use
40. But also (third-party) packages...
41. Atomic compound actions
44. Actions from the same invariant need to be synchronized together
45. Visibility & stale data
48. Is it thread-safe? Join at slido.com #gocon21s
49. Thread-safety is not only about concurrent writes...
51. Remember 3 things
53. Stateless methods → thread-safe methods
56. Thread-safety is about both reads and writes...
59. Prefer delegation over explicit synchronization
62. Be careful with compound actions...
65. Is that all I need to know?
66. What’s not covered 1. Initialisation safety & Immutable objects 2. Thread-confinement 3. Concurrency tooling - atomic variables/collections, synchronizers 4. Goroutine Management 5. Channels 6. Managing goroutine lifecycle via cancellation/interrupts 7. Dealing with performance/liveness issues (i.e. deadlock, livelock, etc.) 8. The Go Memory Model
68. Get the mats → http://bit.ly/goconjp-thread-safety
69. Thread-Safety in Go An Overlooked Concern P. Mihaylov Software Engineer, Tech. Trainer, Speaker preslav@pmihaylov.com Go Conference Tokyo 2021, A random zoom room on the Internet