Elixir - Peeking into Processes, OTP & Supervisors

Talk I gave at Paypal Singapore on the 21st of March 2014 for Hackers and Painters.

Transcript

1. Elixir Peeking into Elixir’s Processes, OTP & Supervisors 21st March 2014 /benjamintanweihao /bentanweihao benjamintanweihao@gmail.com
2. What will we learn today? Elixir & Erlang In less than 5 minutes
3. Elixir & Erlang In less than 5 minutes Processes 101 The Basic Concurrency Primitive What will we learn today?
4. Elixir & Erlang In less than 5 minutes OTP Framework and much more Processes 101 The Basic Concurrency Primitive What will we learn today?
5. Elixir & Erlang In less than 5 minutes OTP Framework and much more Supervisors Fault Tolerance & Recovery Processes 101 The Basic Concurrency Primitive What will we learn today?
6. Ohai, Elixir!
7. Elixir & Erlang In less than 5 minutes
8. Ohai, Erlang! Erlang is a general-purpose concurrent, garbage-collected programming language and runtime system. The sequential subset of Erlang is a functional language, with eager evaluation, single assignment, and dynamic typing. It was designed by Ericsson to support distributed, fault-tolerant, soft-real-time, non- stop applications. It supports hot swapping, so that code can be changed without stopping a system.
9. Ohai, Erlang! Erlang is a general-purpose concurrent, garbage-collected programming language and runtime system. The sequential subset of Erlang is a functional language, with eager evaluation, single assignment, and dynamic typing. It was designed by Ericsson to support distributed, fault-tolerant, soft-real-time, non- stop applications. It supports hot swapping, so that code can be changed without stopping a system.
10. • Free lunch is over Why Elixir ?
11. Why Elixir ? • Free lunch is over • Hyper-threading & Multicore • Faster software means using all cores! • But … Concurrency -> Coordination • Functional makes this easier
12. Design Goals of Elixir 1.Productivity 2.Extensibility 3.Compatibility
13. Productivity Complete Elixir Application
14. Productivity Includes Supervisor Chain
15. Productivity Testing built-in
16. Extensibility Macros & Meta-programming Implementing unless using if
17. Extensibility Macros & Meta-programming Implementing unless using if
18. Compatibility Elixir can call Erlang code, without any conversion cost at all.
19. Compatibility Elixir can use Erlang libraries!
20. The Actor Concurrency Model • Actor = Process
21. The Actor Concurrency Model • Actor = Process • A process performs a specific task when it receives a message
22. The Actor Concurrency Model • Actor = Process • A process performs a specific task when it receives a message • In turn, the process can reply to the sender
23. The Actor Concurrency Model • Actor = Process • A process performs a specific task when it receives a message • In turn, the process can reply to the sender • All messages go to a processes’ mailbox – Q of unprocessed messages sent from other processes that are not yet consumed
24. The Actor Concurrency Model • Actor = Process • A process performs a specific task when it receives a message • In turn, the process can reply to the sender • All messages go to a processes’ mailbox – Q of unprocessed messages sent from other processes that are not yet consumed Shared-nothing Async Message-passing
25. Processes 101 The Basic Concurrency Primitive
26. Creating Processes & Sending Messages in Elixir Creating a Process
27. Creating Processes & Sending Messages in Elixir Module, Function, Arguments
28. Creating Processes & Sending Messages in Elixir Process id
29. Creating Processes & Sending Messages in Elixir Sending a Message to w1
30. Creating Processes & Sending Messages in Elixir Process waits for a message …
31. Creating Processes & Sending Messages in Elixir Pattern matches!
32. Creating Processes & Sending Messages in Elixir Result is sent back to the calling process (self)
33. Creating Processes & Sending Messages in Elixir Returns immediately
34. Creating Processes & Sending Messages in Elixir Get result from self
35. Creating Processes & Sending Messages in Elixir Demo
36. OTP Framework and much more
37. What is OTP? • Comes with Elixir/Erlang • Framework to build applications that are fault- tolerant, scalable, distributed • Databases + Profilers + Debuggers
38. OTP Behaviours • GenServer • Supervisor • Application
39. An Example GenServer Implement the GenServer Behaviour
40. An Example GenServer Implement GenServer Callbacks
41. An Example GenServer Callbacks are NOT called explicitly
42. An Example GenServer OTP calls the callbacks.
43. An Example GenServer Synchronous Call: Caller waits for reply
44. An Example GenServer Asynchronous Call: Caller doesn’t wait for reply
45. An Example GenServer Demo
46. Supervisors Fault Tolerance & Recovery
47. Supervisors for Fault Tolerance and Recovery one_for_one restart strategy
48. Supervisors for Fault Tolerance and Recovery rest_for_all restart strategy
49. Supervisors for Fault Tolerance and Recovery rest_for_one restart strategy
50. An Example Supervisor Implement the Supervisor Behaviour
51. An Example Supervisor Declaring the Supervision tree. Both Supervisors and Workers (e.g. GenServers) can be supervised.
52. An Example Supervisor
53. An Example Supervisor Declare the restart strategy
54. Supervisor Demo Supervisor A Supervisor B Supervisor C Supervisor D Server D Server B Worker 1 Worker 1 Worker
55. Supervisor Demo Supervisor A Supervisor B Supervisor C Supervisor D Server D Server B Worker 1 Worker 1 Worker one_for_one
56. Supervisor Demo Supervisor A Supervisor B Supervisor C Supervisor D Server D Server B Worker 1 Worker 1 Worker one_for_all
57. Supervisor Demo Supervisor A Supervisor B Supervisor C Supervisor D Server D Server B Worker 1 Worker 1 Worker simple_one_for_one
58. Supervisor Demo Supervisor A Supervisor B Supervisor C Supervisor D Server D Server B Worker 1 Worker 1 Worker one_for_one
59. Supervisor Demo Supervisor A Supervisor B Supervisor C Supervisor D Server D Server B Worker 1 Worker 1 Worker one_for_one simple_one_for_one one_for_all one_for_one
60. Elixir & Erlang In less than 5 minutes OTP Framework and much more Supervisors Fault Tolerance & Recovery Processes 101 The Basic Concurrency Primitive
61. Resources
62. Work in Progress! ! Sign up at: http://www.exotpbook.com Me.
63. Stickers!* *Very Limited Quantity
64. Thanks! /benjamintanweihao /bentanweihao benjamintanweihao@gmail.com