Akkurate Akka

The talk was given on local JUG meeting back in 2014. The purpose of the talk was to give an overview of the Akka library for the Java-programmers audience who have never used it before. My first appearance as a public speaker

Transcript

1. AKKurate twist522@gmail.com JUG Lviv
2. outline Problems to solve Actor Model Java & Scala actors Fault-tolerance Scaling, Remoting Reactiveness Some best practices
3. The Problem • highly concurrent • scalable • fault-tolerant
4. AKKA
6. Program at a higher level
7. Scaling up & out & down & .. whatever
8. Automatic Replication & Distribution for fault tolerance & scalability
9. Automatic Load Balancing
10. Modules • akka-kernel • akka-actor • akka-camel • akka-remote • akka-cluster • akka-persistence • akka-stream • …
11. Actor Model Back into the 70’s actors could • perform • create another actors • send messages • become Carl Hewitt
12. Actor • one msg at a time • in one thread • msgs in order • small (~2.5M per Gb)
13. Core operations 0. Define 1. Create 2. Send 3. Become 4. Supervise
14. 0. Define
15. In Scala
16. 1. Create
17. Actor hierarchy
18. 2. Send
19. Full example
20. In Scala
21. Hot Swap
22. In Scala
23. ask
24. Futures
25. Supervision & Monitoring • failures happen • application should self-heal • each actor have supervisor • supervisor handles failures – RESUME – RESTART – STOP – ESCALATE
26. Failure management money snack not enough! FATAL ERROR FATAL ERROR supervisor
27. Supervisor hierarchies • One-for-one strategy • All-for-one strategy
28. Root actors
29. 4. Supervise
30. Death Watch
31. Failure management in Java
32. Load Balancing • scaling up – routers • scaling out – akka-cluster
33. Routers
34. From config
35. Routers • Random • Round-robin • Smallest messagebox • Broadcast • ScatterGatherFirstCompletedOf • …
36. Remote Deployment
37. Lookup
38. Note on reactiveness
39. Reactive manifesto
40. Actors should do only one thing • Single responsibility principle • Create specific supervisors • Keep the error kernel simple
41. Avoid blocking
42. Don’t expose actors • Avoid using this • Don’t close over variables • Use immutable messages with immutable data
43. E0 F