Writing Fast Ruby - Speaker Deck

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Levels of Optimization Design Source Build Compile Runtime

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Levels of Optimization Design Source Build Compile Runtime Architecture and algorithms (e.g. n + 1 queries) Writing fast Ruby Setting build flags (e.g. ./configure) mrbc, jrubyc, rbx compile Thanks Matz & Koichi (e.g. RUBY_GC_MALLOC_LIMIT)

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Benchmark require ‘benchmark' n = 50 Benchmark.bm do |x| x.report { n.times { fast } } x.report { n.times { slow } } end

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Benchmark require ‘benchmark' n = 50_000 Benchmark.bm do |x| x.report { n.times { fast } } x.report { n.times { slow } } end

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Benchmark IPS require 'benchmark/ips' Benchmark.ips do |x| x.report('fast') { fast } x.report('slow') { slow } end

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Goals Source Significant Easy Happy Optimize at the code level At least 12% improvement Code should be easier to read High quality Ruby

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Proc#call versus yield def slow(&block) block.call end def fast yield end

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Results slow 950950.6 (±14.0%) i/s fast 5508226.3 (±15.5%) i/s Over 5X faster!

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Proc#call versus yield def slow Proc.new.call end def fast yield end

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Block versus Symbol#to_proc (1..100).map { |i| i.to_s } (1..100).map(&:to_s)

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Results slow 47524.3 (±7.6%) i/s fast 56823.2 (±7.2%) i/s 20% faster!

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Enumerable#map and Array#flatten versus Enumerable#flat_map enum.map do # do something end.flatten(1) enum.flat_map do # do something end

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Results slow 12348.2 (±9.0%) i/s fast 56647.8 (±7.2%) i/s Over 4.5X faster!

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Enumerable#reverse and Enumerable#each  versus Enumerable#reverse_each enum.reverse.each do # do something end enum.reverse_each do # do something end

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Results slow 156173.2 (±9.2%) i/s fast 182859.3 (±7.8%) i/s 17% faster!

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Hash#keys and Enumerable#each  versus Hash#each_key hash.keys.each do |k| # do something end hash.each_key do |k| # do something end

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Results slow 34702.1 (±9.8%) i/s fast 46103.3 (±8.1%) i/s Over 33% faster!

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Array#shuffle and Array#first  versus Array#sample array.shuffle.first array.sample

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Results slow 324806.7 (±8.1%) i/s fast 5069719.9 (±9.5%) i/s Over 15X faster!

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Hash#merge versus Hash#merge! enum.inject({}) do |h, e| h.merge(e => e) end enum.inject({}) do |h, e| h.merge!(e => e) end

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Results slow 33572.0 (±3.3%) i/s fast 106473.0 (±3.4%) i/s Over 3X faster!

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Hash#merge! versus Hash#[]= enum.each_with_object({}) do |e, h| h.merge!(e => e) end enum.each_with_object({}) do |e, h| h[e] = e end

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Results slow 99331.3 (±2.2%) i/s fast 217944.4 (±5.2%) i/s Over 2X faster!

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Hash#fetch versus Hash#fetch with block {:ruby => :conf}.fetch(:ruby, (0..9).to_a) {:ruby => :conf}.fetch(:ruby) { (0..9).to_a }

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Results slow 712384.2 (±3.8%) i/s fast 1590417.4 (±4.1%) i/s Over 2X faster!

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String#gsub versus String#sub ‘http://rubyconf.pt/'.gsub(‘http://', 'https://') 'http://rubyconf.pt/'.sub('http://', 'https://')

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Results slow 404148.2 (±4.6%) i/s fast 602661.1 (±3.4%) i/s 50% faster!

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String#gsub versus String#tr 'slug from title'.gsub(' ', '_') 'slug from title'.tr(' ', '_')

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Results slow 311878.2 (±3.5%) i/s fast 1573891.1 (±4.6%) i/s Over 5X faster!

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Parallel versus sequential assignment a, b = 1, 2 a = 1 b = 2

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Results slow 5821588.3 (±6.0%) i/s fast 8010420.3 (±5.5%) i/s 40% faster!

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Using exceptions for control flow begin ruby.conf rescue NoMethodError 'conf' end if ruby.respond_to?(:conf) ruby.conf else 'conf' end

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Results slow 328886.4 (±5.0%) i/s fast 3348327.9 (±9.0%) i/s Over 10X faster!

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Using throw/catch for control flow begin ruby.conf rescue NoMethodError 'conf' end catch(:ruby) do if ruby.respond_to?(:conf) ruby.conf else throw(:ruby, ‘conf’) end end

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Results slow 252474.2 (±8.4%) i/s fast 1411916.6 (±7.2%) i/s Over 5X faster!

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The Future

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Special Thanks Aaron Patterson Ruby Rogues Parley Sam Saffron Aman Gupta Don Knuth Yukihiro Matsumoto Koichi Sasada RubyConf Portugal