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In Erik Michaels-Ober's great talk Writing Fast Ruby: Video @ Baruco 2014, Slide, he presents us many idioms that leads to Faster Ruby. He inspired me and I want to document these to let more people know. I try to link to real commit for people to see this can really benefits in real world. But this does not mean you can always replace one with another, depends on the context (e.g. gsub versus tr).
Each idiom has a corresponding code example resides in code.
All results listed in README.md 🏃 with Ruby 2.2.0p0 on OS X 10.10.1. Machine information: MacBook Pro (Retina, 15-inch, Mid 2014), 2.5 GHz Intel Core i7, 16 GB 1600 MHz DDR3. Your results may vary but you get the idea. : )
Let's write faster code, together! <3
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Use benchmark-ips.
require 'benchmark/ips' def slow end def fast end Benchmark.ips do |x| x.report('slow') { slow } x.report('fast') { fast } x.compare! endParallel Assignment vs Sequential Assignment code
Parallel Assignment allocates an extra array.
$ ruby -v code/general/assignment.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Parallel Assignment 99.146k i/100ms Sequential Assignment 127.143k i/100ms ------------------------------------------------- Parallel Assignment 2.522M (± 7.5%) i/s - 12.592M Sequential Assignment 5.686M (± 8.6%) i/s - 28.226M Comparison: Sequential Assignment: 5685750.0 i/s Parallel Assignment: 2521708.9 i/s - 2.25x slower begin...rescue vs respond_to? for Control Flow code
$ ruby -v code/general/begin-rescue-vs-respond-to.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- begin...rescue 29.452k i/100ms respond_to? 106.528k i/100ms ------------------------------------------------- begin...rescue 371.591k (± 5.4%) i/s - 1.855M respond_to? 3.277M (± 7.5%) i/s - 16.299M Comparison: respond_to?: 3276972.3 i/s begin...rescue: 371591.0 i/s - 8.82x slower define_method vs module_eval for Defining Methods code
$ ruby -v code/general/define_method-vs-module-eval.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- module_eval with string 125.000 i/100ms define_method 138.000 i/100ms ------------------------------------------------- module_eval with string 1.130k (±20.3%) i/s - 5.500k define_method 1.346k (±25.9%) i/s - 6.348k Comparison: define_method: 1345.6 i/s module_eval with string: 1129.7 i/s - 1.19x slower Array#bsearch vs Array#find code
$ ruby -v code/array/bsearch-vs-find.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- find 1.000 i/100ms bsearch 42.216k i/100ms ------------------------------------------------- find 0.184 (± 0.0%) i/s - 1.000 in 5.434758s bsearch 577.301k (± 6.6%) i/s - 2.913M Comparison: bsearch: 577300.7 i/s find: 0.2 i/s - 3137489.63x slower Array#count vs Array#size code
$ ruby -v code/array/count-vs-size.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- #count 130.991k i/100ms #size 135.312k i/100ms ------------------------------------------------- #count 6.697M (± 7.1%) i/s - 33.403M #size 7.562M (± 9.1%) i/s - 37.481M Comparison: #size: 7562457.4 i/s #count: 6696763.0 i/s - 1.13x slower Array#shuffle.first vs Array#sample code
Array#shuffleallocates an extra array.
Array#sampleindexes into the array without allocating an extra array.
This is the reason why Array#sample exists.
—— @sferik rails/rails#17245
$ ruby -v code/array/shuffle-first-vs-sample.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#shuffle.first 25.406k i/100ms Array#sample 125.101k i/100ms ------------------------------------------------- Array#shuffle.first 304.341k (± 4.3%) i/s - 1.524M Array#sample 5.727M (± 8.6%) i/s - 28.523M Comparison: Array#sample: 5727032.0 i/s Array#shuffle.first: 304341.1 i/s - 18.82x slower Enumerable#each + push vs Enumerable#map code
$ ruby -v code/enumerable/each-push-vs-map.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#each + push 9.025k i/100ms Array#map 13.947k i/100ms ------------------------------------------------- Array#each + push 99.634k (± 3.2%) i/s - 505.400k Array#map 158.091k (± 4.2%) i/s - 794.979k Comparison: Array#map: 158090.9 i/s Array#each + push: 99634.2 i/s - 1.59x slower Enumerable#each vs for loop code
$ ruby -v code/enumerable/each-vs-for-loop.rb ruby 2.2.0preview1 (2014-09-17 trunk 47616) [x86_64-darwin14] Calculating ------------------------------------- For loop 17.111k i/100ms #each 18.464k i/100ms ------------------------------------------------- For loop 198.517k (± 5.3%) i/s - 992.438k #each 208.157k (± 5.0%) i/s - 1.052M Comparison: #each: 208157.4 i/s For loop: 198517.3 i/s - 1.05x slower Enumerable#each_with_index vs while loop code
$ ruby -v code/array/each_with_index-vs-while-loop.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- each_with_index 11.496k i/100ms While Loop 20.179k i/100ms ------------------------------------------------- each_with_index 128.855k (± 7.5%) i/s - 643.776k While Loop 242.344k (± 4.5%) i/s - 1.211M Comparison: While Loop: 242343.6 i/s each_with_index: 128854.9 i/s - 1.88x slower Enumerable#map...Array#flatten vs Enumerable#flat_map code
-- @sferik rails/rails@3413b88, Replace map.flatten with flat_map, Replace map.flatten(1) with flat_map
ruby -v code/enumerable/map-flatten-vs-flat_map.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#map.flatten(1) 3.315k i/100ms Array#map.flatten 3.283k i/100ms Array#flat_map 5.350k i/100ms ------------------------------------------------- Array#map.flatten(1) 33.801k (± 4.3%) i/s - 169.065k Array#map.flatten 34.530k (± 6.0%) i/s - 173.999k Array#flat_map 55.980k (± 5.0%) i/s - 283.550k Comparison: Array#flat_map: 55979.6 i/s Array#map.flatten: 34529.6 i/s - 1.62x slower Array#map.flatten(1): 33800.6 i/s - 1.66x slower Enumerable#reverse.each vs Enumerable#reverse_each code
Enumerable#reverseallocates an extra array.
Enumerable#reverse_eachyields each value without allocating an extra array.
This is the reason whyEnumerable#reverse_eachexists.
-- @sferik rails/rails#17244
$ ruby -v code/enumerable/reverse-each-vs-reverse_each.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#reverse.each 16.746k i/100ms Array#reverse_each 18.590k i/100ms ------------------------------------------------- Array#reverse.each 190.729k (± 4.8%) i/s - 954.522k Array#reverse_each 216.060k (± 4.3%) i/s - 1.078M Comparison: Array#reverse_each: 216060.5 i/s Array#reverse.each: 190729.1 i/s - 1.13x slower Enumerable#detect vs Enumerable#select.first code
$ ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#select.first 8.515k i/100ms Enumerable#detect 33.885k i/100ms ------------------------------------------------- Enumerable#select.first 89.757k (± 5.0%) i/s - 1.797M Enumerable#detect 434.304k (± 5.2%) i/s - 8.675M Comparison: Enumerable#detect: 434304.2 i/s Enumerable#select.first: 89757.4 i/s - 4.84x slower Enumerable#sort vs Enumerable#sort_by code
$ ruby -v code/enumerable/sort-vs-sort_by.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#sort 1.158k i/100ms Enumerable#sort_by 2.401k i/100ms ------------------------------------------------- Enumerable#sort 12.140k (± 4.9%) i/s - 61.374k Enumerable#sort_by 24.169k (± 4.0%) i/s - 122.451k Comparison: Enumerable#sort_by: 24168.9 i/s Enumerable#sort: 12139.8 i/s - 1.99x slower Hash#fetch with argument vs Hash#fetch + block code
$ ruby -v code/hash/fetch-vs-fetch-with-block.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#fetch + arg 15.650k i/100ms Hash#fetch + block 130.271k i/100ms ------------------------------------------------- Hash#fetch + arg 184.562k (± 5.2%) i/s - 923.350k Hash#fetch + block 5.880M (± 7.5%) i/s - 29.311M Comparison: Hash#fetch + block: 5880209.2 i/s Hash#fetch + arg: 184562.0 i/s - 31.86x slower Hash#each_key instead of Hash#keys.each code
Hash#keys.eachallocates an array of keys;
Hash#each_keyiterates through the keys without allocating a new array.
This is the reason whyHash#each_keyexists.
—— @sferik rails/rails#17099
$ ruby -v code/hash/keys-each-vs-each_key.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#keys.each 56.690k i/100ms Hash#each_key 59.658k i/100ms ------------------------------------------------- Hash#keys.each 869.262k (± 5.0%) i/s - 4.365M Hash#each_key 1.049M (± 6.0%) i/s - 5.250M Comparison: Hash#each_key: 1049161.6 i/s Hash#keys.each: 869262.3 i/s - 1.21x slower Hash#merge! vs Hash#[]= code
$ ruby -v code/hash/merge-bang-vs-\[\]=.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#merge! 1.023k i/100ms Hash#[]= 2.844k i/100ms ------------------------------------------------- Hash#merge! 10.653k (± 4.9%) i/s - 53.196k Hash#[]= 28.287k (±12.4%) i/s - 142.200k Comparison: Hash#[]=: 28287.1 i/s Hash#merge!: 10653.3 i/s - 2.66x slower Hash#merge vs Hash#merge! code
$ ruby -v code/hash/merge-vs-merge-bang.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#merge 39.000 i/100ms Hash#merge! 1.008k i/100ms ------------------------------------------------- Hash#merge 409.610 (± 7.6%) i/s - 2.067k Hash#merge! 9.830k (± 5.8%) i/s - 49.392k Comparison: Hash#merge!: 9830.3 i/s Hash#merge: 409.6 i/s - 24.00x slower Block vs Symbol#to_proc code
Symbol#to_procis considerably more concise than using block syntax.
...In some cases, it reduces the number of lines of code.
—— @sferik rails/rails#16833
$ ruby -v code/proc-and-block/block-vs-to_proc.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Block 4.632k i/100ms Symbol#to_proc 5.225k i/100ms ------------------------------------------------- Block 47.914k (± 6.3%) i/s - 240.864k Symbol#to_proc 54.791k (± 4.1%) i/s - 276.925k Comparison: Symbol#to_proc: 54791.1 i/s Block: 47914.3 i/s - 1.14x slower Proc#call vs yield code
$ ruby -v code/proc-and-block/proc-call-vs-yield.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- block.call 70.663k i/100ms yield 125.061k i/100ms ------------------------------------------------- block.call 1.309M (± 5.7%) i/s - 6.572M yield 6.103M (± 7.7%) i/s - 30.390M Comparison: yield: 6102822.9 i/s block.call: 1309452.1 i/s - 4.66x slower String#casecmp vs String#downcase + == code
$ ruby -v code/string/casecmp-vs-downcase-\=\=.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#downcase + == 101.900k i/100ms String#casecmp 109.828k i/100ms ------------------------------------------------- String#downcase + == 2.915M (± 5.4%) i/s - 14.572M String#casecmp 3.708M (± 6.1%) i/s - 18.561M Comparison: String#casecmp: 3708258.7 i/s String#downcase + ==: 2914767.7 i/s - 1.27x slower String Concatenation code
$ ruby code/string/concatenation.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#+ 96.314k i/100ms String#concat 99.850k i/100ms String#append 100.728k i/100ms "foo" "bar" 121.936k i/100ms ------------------------------------------------- String#+ 2.731M (± 4.6%) i/s - 13.677M String#concat 2.847M (± 5.2%) i/s - 14.279M String#append 2.972M (± 6.1%) i/s - 14.807M "foo" "bar" 4.951M (± 6.2%) i/s - 24.753M Comparison: "foo" "bar": 4950955.3 i/s String#append: 2972048.5 i/s - 1.67x slower String#concat: 2846666.4 i/s - 1.74x slower String#+: 2730980.7 i/s - 1.81x slower String#match vs String#start_with?/String#end_with? code (start) code (end)
⚠️
Sometimes you cant replace regexp withstart_with?,
for example:"a\nb" =~ /^b/ #=> 2but"a\nb" =~ /\Ab/ #=> nil.
⚠️
You can combinestart_with?andend_with?to replaceerror.path =~ /^#{path}(\.rb)?$/to this
error.path.start_with?(path) && error.path.end_with?('.rb', '')
—— @igas rails/rails#17316
$ ruby -v code/string/start-string-checking-match-vs-start_with.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#=~ 55.411k i/100ms String#start_with? 113.854k i/100ms ------------------------------------------------- String#=~ 910.625k (± 4.6%) i/s - 4.544M String#start_with? 3.983M (± 5.5%) i/s - 19.924M Comparison: String#start_with?: 3983284.9 i/s String#=~: 910625.0 i/s - 4.37x slower $ ruby -v code/string/end-string-checking-match-vs-start_with.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#=~ 52.811k i/100ms String#end_with? 100.071k i/100ms ------------------------------------------------- String#=~ 854.830k (± 5.8%) i/s - 4.278M String#end_with? 2.837M (± 5.5%) i/s - 14.210M Comparison: String#end_with?: 2836536.9 i/s String#=~: 854830.3 i/s - 3.32x slower String#gsub vs String#sub code
$ ruby -v code/string/gsub-vs-sub.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#gsub 35.724k i/100ms String#sub 42.426k i/100ms ------------------------------------------------- String#gsub 486.614k (± 5.4%) i/s - 2.429M String#sub 611.259k (± 4.6%) i/s - 3.055M Comparison: String#sub: 611259.4 i/s String#gsub: 486613.5 i/s - 1.26x slower String#gsub vs String#tr code
$ ruby -v code/string/gsub-vs-tr.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#gsub 38.268k i/100ms String#tr 83.210k i/100ms ------------------------------------------------- String#gsub 516.604k (± 4.4%) i/s - 2.602M String#tr 1.862M (± 4.0%) i/s - 9.320M Comparison: String#tr: 1861860.4 i/s String#gsub: 516604.2 i/s - 3.60x slower attr_accessor vs getter and setter code
https://www.omniref.com/ruby/2.2.0/files/method.h?#annotation=4081781&line=47
$ ruby -v code/general/attr-accessor-vs-getter-and-setter.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- getter_and_setter 61.240k i/100ms attr_accessor 66.535k i/100ms ------------------------------------------------- getter_and_setter 1.660M (± 9.7%) i/s - 8.267M attr_accessor 1.865M (± 9.2%) i/s - 9.248M Comparison: attr_accessor: 1865408.4 i/s getter_and_setter: 1660021.9 i/s - 1.12x slower Please! Edit this README.md then Submit a Awesome Pull Request!
Code example is wrong? 😢 Got better example? 😍 Excellent!
Please open an issue or Open a Pull Request to fix it.
Thank you in advance! 😉 🍺
Share this with your #Rubyfriends! <3
Brought to you by @JuanitoFatas
Feel free to talk with me on Twitter! <3
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