Yet another introduction to concurrency

Slides of my talk for RubyconfBR 2016

Transcript

1. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu yet another introduction to CONCURRENCY
2. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Nando Sousa Software Developer @ Resultados Digitais @nandosousafr
3. Fun fact about me..
4. Ship It! http://bit.ly/2d3BET8 rdstation.com.br shipit.resultadosdigitais.com.br
5. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu SO… LET’S ABOUT CONCURRENCY…
6. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Why this is hot topic these days? MULTICORE CRISIS
7. Resultados Digitais: We're hiring! What’s Moore’s law? processing power will double every 18 months
8. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu MULTICORE
9. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu The free lunch is over! http://www.gotw.ca/publications/concurrency-ddj.htm
10. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Parallelism Concurrency vs
11. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu “Concurrency is about dealing with lots of things at once. Parallelism is about doing lots of things at once.” Rob Pike Co-creator of Golang
12. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu “Concurrency: Programming as the composition of independently executing processes.” Rob Pike Co-creator of Golang
13. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu “The world is concurrent!” Rob Pike Co-creator of Golang
14. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Let’s see some code!
15. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu require 'concurrent' require 'httparty' USERS = [ 'nandosousafr', 'jeanmantheussouto', 'thiesen', 'pcasaretto', 'hugoluchessi', 'jeanholderbaum', 'aureliosaraiva' ] def get_followers_count(user) endpoint_url = “http://api.github.com/users/#{user}/ followers” response = HTTParty.get(endpoint_url) raise unless response.status == 200 response.count end def execute_concurrently futures = USERS.collect do |user| Concurrent::Future.execute { get_followers_count(user) } end futures.collect {|future| future.value } end
16. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu def execute_concurrently futures = USERS.collect do |user| Concurrent::Future.execute { get_followers_count(user) } end futures.collect {|future| future.value } end composition independently executing processes
17. Resultados Digitais: We're hiring! CONCURRENCY VS PARALLELISM • Concurrency is about design; • Parallelism is about optimization; • Different, but related;
18. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Shared memory concurrent model
19. Resultados Digitais: We're hiring! SHARED MEMORY CONCURRENT MODEL • Languages like (Ruby, Java and C++) supports it; • Traditional; • A little for than a abstraction what the OS does;
20. Resultados Digitais: We're hiring! Thread OS Process Thread Thread Shared Memory Space
21. Resultados Digitais: We're hiring! 1 var_a = "foo" 2 #=> foo 3 4 var_b = var_a 5 #=> foo 6 7 var_b.upcase! 8 #=> FOO 9 10 var_a 11 #=> FOO SHARED MEMORY CONCURRENT MODEL
22. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Race Condition
23. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu
24. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu 1 public class Counting { 2 public static void main(String[] args) throws InterruptedException { 3 class Counter { 4 private int count = 0; 5 public void increment() { ++count; } 6 public int getCount() { return count; } 7 } 8 9 final Counter counter = new Counter(); 10 11 class CountingThread extends Thread { 12 public void run() { 13 for(int x = 0; x < 10000; ++x) 14 counter.increment(); 15 16 } 17 } 18 19 CountingThread t1 = new CountingThread(); 20 CountingThread t2 = new CountingThread(); 21 22 t1.start(); t2.start(); 23 t1.join(); t2.join(); 24 25 System.out.println(counter.getCount()); 26 } 27 }
25. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu $ seq 5 | xargs -L 1 java Counting 14925 10726 10850 12582 17219
26. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu $ seq 5 | xargs -L 1 java Counting 14925 10726 10850 12582 17219
27. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu $ seq 5 | xargs -L 1 java Counting 14925 10726 10850 12582 17219
28. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu $ seq 5 | xargs -L 1 java Counting 14925 10726 10850 12582 17219
29. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu “A race condition is an undesirable situation that occurs when a device or system attempts to perform two or more operations at the same time, but because of the nature of the device or system, the operations must be done in the proper sequence to be done correctly.” http://searchstorage.techtarget.com/definition/race-condition
30. Resultados Digitais: We're hiring! INCREMENT METHOD READ MODIFY WRITE
31. Resultados Digitais: We're hiring! ++COUNT READ MODIFY WRITE 42 42 ++ ++ 43 43
32. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Mutex ( Mutual Exclusion ) Using locks to ensure that only one thread can access data at a time.
33. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu 1 public class Counting { 2 public static void main(String[] args) throws InterruptedException { 3 class Counter { 4 private int count = 0; 5 public synchronized void increment() { ++count; } 6 public int getCount() { return count; } 7 } 8 9 final Counter counter = new Counter(); 10 11 class CountingThread extends Thread { 12 public void run() { 13 for(int x = 0; x < 10000; ++x) 14 counter.increment(); 15 16 } 17 } 18 19 CountingThread t1 = new CountingThread(); 20 CountingThread t2 = new CountingThread(); 21 22 t1.start(); t2.start(); 23 t1.join(); t2.join(); 24 25 System.out.println(counter.getCount()); 26 } 27 }
34. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu $ seq 5 | xargs -L 1 java Counting 20000 20000 20000 20000 20000
35. Resultados Digitais: We're hiring! RECAP - SHARED MEMORY CONCURRENT MODEL • Locks • Deadlocks • Communication;
36. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Message Passing Concurrent Model
37. Resultados Digitais: We're hiring! Thread SHARED MEMORY ENVIRONMENT Thread Thread Shared Memory
38. Resultados Digitais: We're hiring! Process Erlang VM Process Process Process Process Process
39. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu “Do not communicate by sharing memory; instead, share memory by communicating.” Rob Pike
40. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Let’s see some code!
41. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu 1 defmodule Counter do 2 def start(count) do 3 spawn(__MODULE__, :loop, [count]) 4 end 5 6 def next(counter) do 7 send(counter, {:next}) 8 end 9 10 def loop(count) do 11 receive do 12 {:next} -> 13 IO.puts("Current count is: #{count}") 14 loop(count + 1) 15 end 16 end 17 end
42. Resultados Digitais: We're hiring! $ iex iex(3)> counter = Counter.start(42) #PID<0.63.0> iex(4)> Counter.next(counter) Current count is: 42 {:next} iex(5)> Counter.next(counter) Current count is: 43 {:next} iex(6)> Counter.next(counter) Current count is: 44 {:next}
43. Resultados Digitais: We're hiring! MESSAGE PASSING CONCURRENT MODEL • Enforces you to write concurrent software; • No locks;
44. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Other resources: Concurrency is not parallelism - by Rob Pike Everything You Know About the GIL is Wrong by Jerry D'Antonio The Free Lunch Is Over by Herb Sutter
45. Resultados Digitais: We're hiring! Download slides at: bit.ly/2cswCwu Thanks Questions? @nandosousafr