The (Ruby) Sims

Ever thought about writing a simulator in Ruby?

Transcript

1. The (Ruby) Sims (part 1)
2. Introduction
3. @bryanl
11. CootieSim2012
12. Why RUBY?
13. Stochastic vs Deterministic
14. Define inputs Compute Analyze output
15. SIMULATION_LENGTH = 100 PEOPLE_COUNT = 100 def create_people(people_count); end def report; end def simulate_to(count) 1.upto(count) {|i| yield i } end people = create_people(PEOPLE_COUNT) simulate_to(SIMULATION_LENGTH) do |iteration| # mish and mash people end report
16. class Simulator def initialize(length, count) # ... end end s = Simulator.new 3650, 100 Define inputs
17. class Simulator def simulate(iteration) create_pairs(iteration) transmit(iteration) progress_infections(iteration) end end Compute
18. s = Simulator.new 3650, 100 s.run s.infected_people.each do |p| i = p.infections.to_a d = p.diseases.to_a puts "#{p} #{i} #{d}" end Analyze output
19. Breakdown
20. What’s in a day?
21. Create new pair
22. def create_pairs(iteration) @pairs += people_not_in_pairs(iteration) .shuffle .each_slice(2) .map{|x| Pair.new iteration, x} end
23. Transmit cooties
24. class Simulation def transmit(iteration) current_pairs(iteration).each{|pair| pair.contact(iteration)} end end class Pair def contact(iteration) @alpha.infect(iteration, @beta) @beta.infect(iteration, @alpha) end end class Person def infect(iteration, person); end def acquire(infection); end end
25. Track infection
    progress
26. class Person def progress_infections(iteration) @infections.each do |infection| if rand <= infection.chance_to_acquire_disease unless has_disease? infection.disease @diseases << infection.disease.new(iteration) end end end end end
27. ... This isn’t going
    to be fast
28. 28.23s user 0.10s system 99% cpu 28.333 total
29. but why?
30. %self total self wait child calls name 30.32 386.26 117.53 0.00 268.72 21904 Array#each 28.08 180.05 108.88 0.00 71.18 78738195 Comparable#between? 21.74 84.29 84.29 0.00 0.00 78738195 Pair#duration 18.36 71.18 71.18 0.00 0.00 157476390 Fixnum#<=> 0.29 2.11 1.11 0.00 1.06 414957 Set#each 0.13 1.15 0.50 0.00 0.65 365100 Person#infected? 0.13 2.36 0.50 0.00 1.86 365000 Person#infect 0.12 0.65 0.48 0.00 0.17 365100 Set#empty?
31. O(n)
32. module Enumerable # create a thread and execute in parallel def parallel_each(&block) # create thread yield # cleanup end end
33. gem install peach (YMMV)
35. 100 people
36. 3650 iterations
37. 365,000 “actions”
38. 3,650,000 @ 1,000 36,500,000 @ 10,000 365,000,000 @ 100,000 3,650,000,000 @ 1,000,000
39. How do we make it faster?
40. You can’t!!!
41. 1. Run less code 2. Do more things at once
42. MRI 1.9
44. Thread.new
46. JRuby
48. Thread.new
50. JRuby’s sweetspot is Hotspot
51. 11.34s user 0.37s system 116% cpu 10.064 total
52. Doing more than one thing at once with MRI
53. Queues
54. redis backed
55. resque
56. sidekiq
57. memory backed
58. girl_friday
59. memory backed
60. rabbitmq
61. db backed
62. rabbitmq
63. socket based concurrency
64. Ømq
65. dcell (part 2)
66. statistics
67. mean median variance standard deviation σ
68. How do i randomly pick an integer from 1-6?
69. gem install vose
70. v = Vose::AliasMethod.new [1,1,1,1,1,1] (1..10000).map{v.next}.inject(Hash.new{0}){ |m,n| m[n]+=1; m} (1..10000).map{rand(1..6)} .inject(Hash.new{0}){|m,n| m[n]+=1; m} VS
71. What if the die is weighted?
72. v = Vose::AliasMethod.new [1.2,1,1,1,1,1] (1..10000).map{v.next}.inject(Hash.new{0}){ |m,n| m[n]+=1; m} ????? VS
73. graphing
74. Trends
77. library(ggplot2) runtime.csv <- read.csv("runtime.csv", header=T) mygg<- qplot(iteration, time, data=runtime.csv); mygg<- mygg + stat_smooth(method="lm") ggsave("runtime.png") dev.off() R
78. Visualization
80. digraph g { "person59" -> "person5"; "person23" -> "person18"; "person72" -> "person23"; "person78" -> "person44"; "person78" -> "person59"; "person59" -> "person72"; "person1" -> "person78"; "person83" -> "person81"; "person59" -> "person83"; "person59" -> "person92"; }; Graphviz
81. Building a simulator
85. ?!
86. Shared Cooties?
87. Making it fast
88. Be kind to MRI’s GC
89. Run more than one process
90. Look outside of MRI
91. irb(main):003:0> rand 1..7 TypeError: can't convert Range into Integer from org/jruby/RubyKernel.java:1580:in `rand' from (irb):3:in `evaluate' from org/jruby/RubyKernel.java:1070:in `eval' from org/jruby/RubyKernel.java:1395:in `loop' from org/jruby/RubyKernel.java:1178:in `catch' from org/jruby/RubyKernel.java:1178:in `catch' from /Users/bryan/.rbenv/versions/jruby-1.7.0-preview2/bin/irb:13:in `(root)' JRuby 1.7 pre2
92. irb(main):001:0> rand 1..7 => 3 MRI 1.9.3
93. other languages?
94. The Ruby compromise
95. Exploring
    CootieSim2012
96. Thanks! @thunderboltlabs @bryanl