In Erik Michaels-Ober's great talk, 'Writing Fast Ruby': Video @ Baruco 2014, Slide, he presented us with many idioms that lead to faster running Ruby code. He inspired me to document these to let more people know. I try to link to real commits so people can see that this can really have benefits in the real world. This does not mean you can always blindly replace one with another. It depends on the context (e.g. gsub versus tr). Friendly reminder: Use with caution!
Each idiom has a corresponding code example that resides in code.
All results listed in README.md are running 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. : )
You can checkout the GitHub Actions build for these benchmark results ran against different Ruby implementations.
Let's write faster code, together! <3
Checkout the fasterer project - it's a static analysis that checks speed idioms written in this repo.
Use benchmark-ips (2.0+).
require "benchmark/ips" def fast end def slow end Benchmark.ips do |x| x.report("fast code description") { fast } x.report("slow code description") { slow } x.compare! endattr_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 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 String#constantize vs a comparison for inflection code
ActiveSupport's String#constantize "resolves the constant reference expression in its receiver".
ruby 2.7.3p183 (2021-04-05 revision 6847ee089d) [x86_64-darwin20] Calculating ------------------------------------- using an if statement 8.124M (± 1.8%) i/s - 41.357M in 5.092437s String#constantize 2.462M (± 2.4%) i/s - 12.315M in 5.004089s Comparison: using an if statement: 8123851.3 i/s String#constantize: 2462371.2 i/s - 3.30x (± 0.00) slower raise vs E2MM#Raise for raising (and defining) exceptions code
Ruby's Exception2MessageMapper module allows one to define and raise exceptions with predefined messages.
$ ruby -v code/general/raise-vs-e2mmap.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14] Calculating ------------------------------------- Ruby exception: E2MM#Raise 2.865k i/100ms Ruby exception: Kernel#raise 42.215k i/100ms ------------------------------------------------- Ruby exception: E2MM#Raise 27.270k (± 8.8%) i/s - 137.520k Ruby exception: Kernel#raise 617.446k (± 7.9%) i/s - 3.082M Comparison: Ruby exception: Kernel#raise: 617446.2 i/s Ruby exception: E2MM#Raise: 27269.8 i/s - 22.64x slower Calculating ------------------------------------- Custom exception: E2MM#Raise 2.807k i/100ms Custom exception: Kernel#raise 45.313k i/100ms ------------------------------------------------- Custom exception: E2MM#Raise 29.005k (± 7.2%) i/s - 145.964k Custom exception: Kernel#raise 589.149k (± 7.8%) i/s - 2.945M Comparison: Custom exception: Kernel#raise: 589148.7 i/s Custom exception: E2MM#Raise: 29004.8 i/s - 20.31x slower loop vs while true code
$ ruby -v code/general/loop-vs-while-true.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-linux] Calculating ------------------------------------- While Loop 1.000 i/100ms Kernel loop 1.000 i/100ms ------------------------------------------------- While Loop 0.536 (± 0.0%) i/s - 3.000 in 5.593042s Kernel loop 0.223 (± 0.0%) i/s - 2.000 in 8.982355s Comparison: While Loop: 0.5 i/s Kernel loop: 0.2 i/s - 2.41x slower ancestors.include? vs <= code
$ ruby -vW0 code/general/inheritance-check.rb ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux] Warming up -------------------------------------- less than or equal 66.992k i/100ms ancestors.include? 16.943k i/100ms Calculating ------------------------------------- less than or equal 1.250M (± 6.4%) i/s - 6.230M in 5.006896s ancestors.include? 192.603k (± 4.8%) i/s - 965.751k in 5.025917s Comparison: less than or equal: 1249606.0 i/s ancestors.include?: 192602.9 i/s - 6.49x slower call vs send vs method_missing code
$ ruby -v code/method/call-vs-send-vs-method_missing.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- call 115.094k i/100ms send 105.258k i/100ms method_missing 100.762k i/100ms ------------------------------------------------- call 3.811M (± 5.9%) i/s - 18.991M send 3.244M (± 7.2%) i/s - 16.210M method_missing 2.729M (± 9.8%) i/s - 13.401M Comparison: call: 3811183.4 i/s send: 3244239.1 i/s - 1.17x slower method_missing: 2728893.0 i/s - 1.40x slower Normal way to apply method vs &method(...) code
$ ruby -v code/general/block-apply-method.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- normal 85.749k i/100ms &method 35.529k i/100ms ------------------------------------------------- normal 1.867M (± 7.6%) i/s - 9.347M &method 467.095k (± 6.4%) i/s - 2.345M Comparison: normal: 1866669.5 i/s &method: 467095.4 i/s - 4.00x slower Function with single Array argument vs splat arguments code
$ ruby -v code/general/array-argument-vs-splat-arguments.rb ruby 2.1.7p400 (2015-08-18 revision 51632) [x86_64-linux-gnu] Calculating ------------------------------------- Function with single Array argument 157.231k i/100ms Function with splat arguments 4.983k i/100ms ------------------------------------------------- Function with single Array argument 5.581M (± 2.0%) i/s - 27.987M Function with splat arguments 54.428k (± 3.3%) i/s - 274.065k Comparison: Function with single Array argument: 5580972.6 i/s Function with splat arguments: 54427.7 i/s - 102.54x slower Hash vs OpenStruct on access assuming you already have a Hash or an OpenStruct code
$ ruby -v code/general/hash-vs-openstruct-on-access.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14] Calculating ------------------------------------- Hash 128.344k i/100ms OpenStruct 110.723k i/100ms ------------------------------------------------- Hash 5.279M (± 7.0%) i/s - 26.311M OpenStruct 3.048M (± 7.0%) i/s - 15.169M Comparison: Hash: 5278844.0 i/s OpenStruct: 3048139.8 i/s - 1.73x slower Hash vs OpenStruct (creation) code
$ ruby -v code/general/hash-vs-openstruct.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14] Calculating ------------------------------------- Hash 75.510k i/100ms OpenStruct 9.126k i/100ms ------------------------------------------------- Hash 1.604M (±11.0%) i/s - 7.929M OpenStruct 96.855k (± 9.9%) i/s - 483.678k Comparison: Hash: 1604259.1 i/s OpenStruct: 96855.3 i/s - 16.56x slower Kernel#format vs Float#round().to_s code
$ ruby -v code/general/format-vs-round-and-to-s.rb ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin15] Warming up -------------------------------------- Float#round 106.645k i/100ms Kernel#format 84.304k i/100ms String#% 78.635k i/100ms Calculating ------------------------------------- Float#round 1.570M (± 3.2%) i/s - 7.892M in 5.030672s Kernel#format 1.144M (± 3.0%) i/s - 5.733M in 5.015621s String#% 1.047M (± 4.2%) i/s - 5.269M in 5.042970s Comparison: Float#round: 1570411.4 i/s Kernel#format: 1144036.6 i/s - 1.37x slower String#%: 1046689.1 i/s - 1.50x slower Array#bsearch vs Array#find code
WARNING: bsearch ONLY works on sorted array. More details please see #29.
$ 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#length vs Array#size vs Array#count code
Use #length when you only want to know how many elements in the array, #count could also achieve this. However #count should be use for counting specific elements in array. Note #size is an alias of #length.
$ ruby -v code/array/length-vs-size-vs-count.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Array#length 172.998k i/100ms Array#size 168.130k i/100ms Array#count 164.911k i/100ms ------------------------------------------------- Array#length 11.394M (± 6.1%) i/s - 56.743M Array#size 11.303M (± 6.5%) i/s - 56.324M Array#count 9.195M (± 8.6%) i/s - 45.680M Comparison: Array#length: 11394036.7 i/s Array#size: 11302701.1 i/s - 1.01x slower Array#count: 9194976.2 i/s - 1.24x 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 Array#[](0) vs Array#first code
$ ruby -v code/array/array-first-vs-index.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#[0] 152.751k i/100ms Array#first 148.088k i/100ms ------------------------------------------------- Array#[0] 8.614M (± 7.0%) i/s - 42.923M Array#first 7.465M (±10.7%) i/s - 36.874M Comparison: Array#[0]: 8613583.7 i/s Array#first: 7464526.6 i/s - 1.15x slower Array#[](-1) vs Array#last code
$ ruby -v code/array/array-last-vs-index.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#[-1] 151.940k i/100ms Array#last 153.371k i/100ms ------------------------------------------------- Array#[-1] 8.582M (± 4.6%) i/s - 42.847M Array#last 7.639M (± 5.7%) i/s - 38.189M Comparison: Array#[-1]: 8582074.3 i/s Array#last: 7639254.5 i/s - 1.12x slower Array#insert vs Array#unshift code
$ ruby -v code/array/insert-vs-unshift.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin10.0] Calculating ------------------------------------- Array#unshift 4.000 i/100ms Array#insert 1.000 i/100ms ------------------------------------------------- Array#unshift 44.947 (± 6.7%) i/s - 224.000 Array#insert 0.171 (± 0.0%) i/s - 1.000 in 5.841595s Comparison: Array#unshift: 44.9 i/s Array#insert: 0.2 i/s - 262.56x slower Array#concat vs Array#+ code
Array#+ returns a new array built by concatenating the two arrays together to produce a third array. Array#concat appends the elements of the other array to self. This means that the + operator will create a new array each time it is called (which is expensive), while concat only appends the new element.
$ ruby -v code/array/array-concat-vs-+.rb ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin18] Warming up -------------------------------------- Array#concat 23.000 i/100ms Array#+ 1.000 i/100ms Calculating ------------------------------------- Array#concat 217.669 (±15.2%) i/s - 1.058k in 5.016952s Array#+ 1.475 (± 0.0%) i/s - 8.000 in 5.467642s Comparison: Array#concat: 217.7 i/s Array#+: 1.5 i/s - 147.54x slower Array#new vs Fixnum#times + map code
Typical slowdown is 40-60% depending on the size of the array. See the corresponding pull request for performance characteristics.
ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin15] Calculating ------------------------------------- Array#new 63.875k i/100ms Fixnum#times + map 48.010k i/100ms ------------------------------------------------- Array#new 1.070M (± 2.2%) i/s - 5.365M Fixnum#times + map 678.097k (± 2.7%) i/s - 3.409M Comparison: Array#new: 1069837.0 i/s Fixnum#times + map: 678097.4 i/s - 1.58x slower Array#sort.reverse vs Array#sort_by + block code
$ ruby -v code/array/sort-reverse-vs-sort_by.rb ruby 2.5.2p104 (2018-10-18 revision 65133) [x86_64-darwin13] Warming up -------------------------------------- Array#sort.reverse 16.231k i/100ms Array#sort_by &:-@ 5.406k i/100ms Calculating ------------------------------------- Array#sort.reverse 149.492k (±11.0%) i/s - 746.626k in 5.070375s Array#sort_by &:-@ 51.981k (± 8.8%) i/s - 259.488k in 5.041625s Comparison: Array#sort.reverse: 149492.2 i/s Array#sort_by &:-@: 51980.6 i/s - 2.88x (± 0.00) 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/enumerable/each_with_index-vs-while-loop.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- While Loop 22.553k i/100ms each_with_index 11.963k i/100ms ------------------------------------------------- While Loop 240.752k (± 7.1%) i/s - 1.218M each_with_index 126.753k (± 5.9%) i/s - 634.039k Comparison: While Loop: 240752.1 i/s each_with_index: 126753.4 i/s - 1.90x 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#sort_by.first vs Enumerable#min_by code
Enumerable#sort_by performs a sort of the enumerable and allocates a new array the size of the enumerable. Enumerable#min_by doesn't perform a sort or allocate an array the size of the enumerable. Similar comparisons hold for Enumerable#sort_by.last vs Enumerable#max_by, Enumerable#sort.first vs Enumerable#min, and Enumerable#sort.last vs Enumerable#max.
$ ruby -v code/enumerable/sort_by-first-vs-min_by.rb ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17] Warming up -------------------------------------- Enumerable#min_by 15.170k i/100ms Enumerable#sort_by...first 10.413k i/100ms Calculating ------------------------------------- Enumerable#min_by 157.877k (± 0.9%) i/s - 804.010k in 5.093048s Enumerable#sort_by...first 106.831k (± 1.3%) i/s - 541.476k in 5.069403s Comparison: Enumerable#min_by: 157877.0 i/s Enumerable#sort_by...first: 106831.1 i/s - 1.48x slower Enumerable#detect vs Enumerable#select.first code
$ ruby -v code/enumerable/select-first-vs-detect.rb 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#select.last vs Enumerable#reverse.detect code
$ ruby -v code/enumerable/select-last-vs-reverse-detect.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#reverse.detect 62.636k i/100ms Enumerable#select.last 11.687k i/100ms ------------------------------------------------- Enumerable#reverse.detect 1.263M (± 8.2%) i/s - 6.326M Enumerable#select.last 119.387k (± 5.7%) i/s - 596.037k Comparison: Enumerable#reverse.detect: 1263100.2 i/s Enumerable#select.last: 119386.8 i/s - 10.58x slower Enumerable#sort vs Enumerable#sort_by code
$ ruby -v code/enumerable/sort-vs-sort_by.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#sort_by (Symbol#to_proc) 2.680k i/100ms Enumerable#sort_by 2.462k i/100ms Enumerable#sort 1.320k i/100ms ------------------------------------------------- Enumerable#sort_by (Symbol#to_proc) 25.916k (± 4.4%) i/s - 131.320k Enumerable#sort_by 24.650k (± 5.1%) i/s - 125.562k Enumerable#sort 14.018k (± 5.6%) i/s - 69.960k Comparison: Enumerable#sort_by (Symbol#to_proc): 25916.1 i/s Enumerable#sort_by: 24650.2 i/s - 1.05x slower Enumerable#sort: 14018.3 i/s - 1.85x slower Enumerable#inject Symbol vs Enumerable#inject Proc code
Of note, to_proc for 1.8.7 is considerable slower than the block format
$ ruby -v code/enumerable/inject-symbol-vs-block.rb ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-darwin14] Warming up -------------------------------------- inject symbol 1.893k i/100ms inject to_proc 1.583k i/100ms inject block 1.390k i/100ms Calculating ------------------------------------- inject symbol 19.001k (± 3.8%) i/s - 96.543k inject to_proc 15.958k (± 3.5%) i/s - 80.733k inject block 14.063k (± 3.9%) i/s - 70.890k Comparison: inject symbol: 19001.5 i/s inject to_proc: 15958.3 i/s - 1.19x slower inject block: 14063.1 i/s - 1.35x slower Date.iso8601 vs Date.parse code
When expecting well-formatted data from e.g. an API, iso8601 is faster and will raise an ArgumentError on malformed input.
$ ruby -v code/date/iso8601-vs-parse.rb ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17] Warming up -------------------------------------- Date.iso8601 28.880k i/100ms Date.parse 15.805k i/100ms Calculating ------------------------------------- Date.iso8601 328.035k (± 4.7%) i/s - 1.646M in 5.029287s Date.parse 175.546k (± 3.8%) i/s - 885.080k in 5.049444s Comparison: Date.iso8601: 328035.3 i/s Date.parse: 175545.9 i/s - 1.87x slower Hash#[] vs Hash#fetch code
If you use Ruby 2.2, Symbol could be more performant than String as Hash keys. Read more regarding this: Symbol GC in Ruby 2.2 and Unraveling String Key Performance in Ruby 2.2.
$ ruby -v code/hash/bracket-vs-fetch.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Hash#[], symbol 143.850k i/100ms Hash#fetch, symbol 137.425k i/100ms Hash#[], string 143.083k i/100ms Hash#fetch, string 120.417k i/100ms ------------------------------------------------- Hash#[], symbol 7.531M (± 6.6%) i/s - 37.545M Hash#fetch, symbol 6.644M (± 8.2%) i/s - 32.982M Hash#[], string 6.657M (± 7.7%) i/s - 33.195M Hash#fetch, string 3.981M (± 8.7%) i/s - 19.748M Comparison: Hash#[], symbol: 7531355.8 i/s Hash#[], string: 6656818.8 i/s - 1.13x slower Hash#fetch, symbol: 6643665.5 i/s - 1.13x slower Hash#fetch, string: 3981166.5 i/s - 1.89x slower Hash#dig vs Hash#[] vs Hash#fetch code
Ruby 2.3 introduced Hash#dig which is a readable and performant option for retrieval from a nested hash, returning nil if an extraction step fails. See #102 (comment) for more info.
$ ruby -v code/hash/dig-vs-\[\]-vs-fetch.rb ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin15] Calculating ------------------------------------- Hash#dig 5.719M (± 6.1%) i/s - 28.573M in 5.013997s Hash#[] 6.066M (± 6.9%) i/s - 30.324M in 5.025614s Hash#[] || 5.366M (± 6.5%) i/s - 26.933M in 5.041403s Hash#[] && 2.782M (± 4.8%) i/s - 13.905M in 5.010328s Hash#fetch 4.101M (± 6.1%) i/s - 20.531M in 5.024945s Hash#fetch fallback 2.975M (± 5.5%) i/s - 14.972M in 5.048880s Comparison: Hash#[]: 6065791.0 i/s Hash#dig: 5719290.9 i/s - same-ish: difference falls within error Hash#[] ||: 5366226.5 i/s - same-ish: difference falls within error Hash#fetch: 4101102.1 i/s - 1.48x slower Hash#fetch fallback: 2974906.9 i/s - 2.04x slower Hash#[] &&: 2781646.6 i/s - 2.18x slower Hash[] vs Hash#dup code
Source: http://tenderlovemaking.com/2015/02/11/weird-stuff-with-hashes.html
Does this mean that you should switch to Hash[]? Only if your benchmarks can prove that it’s a bottleneck. Please please please don’t change all of your code because this shows it’s faster. Make sure to measure your app performance first.
$ ruby -v code/hash/bracket-vs-dup.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash[] 29.403k i/100ms Hash#dup 16.195k i/100ms ------------------------------------------------- Hash[] 343.987k (± 8.7%) i/s - 1.735M Hash#dup 163.516k (±10.2%) i/s - 825.945k Comparison: Hash[]: 343986.5 i/s Hash#dup: 163516.3 i/s - 2.10x slower Hash#fetch with argument vs Hash#fetch + block code
Note that the speedup in the block version comes from avoiding repeated
construction of the argument. If the argument is a constant, number symbol or
something of that sort the argument version is actually slightly faster
See also #39 (comment)
$ ruby -v code/hash/fetch-vs-fetch-with-block.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin13] Calculating ------------------------------------- Hash#fetch + const 129.868k i/100ms Hash#fetch + block 125.254k i/100ms Hash#fetch + arg 121.155k i/100ms ------------------------------------------------- Hash#fetch + const 7.031M (± 7.0%) i/s - 34.934M Hash#fetch + block 6.815M (± 4.2%) i/s - 34.069M Hash#fetch + arg 4.753M (± 5.6%) i/s - 23.746M Comparison: Hash#fetch + const: 7030600.4 i/s Hash#fetch + block: 6814826.7 i/s - 1.03x slower Hash#fetch + arg: 4752567.2 i/s - 1.48x 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#key? instead of Hash#keys.include? code
Hash#keys.include?allocates an array of keys and performs an O(n) search;
Hash#key?performs an O(1) hash lookup without allocating a new array.
$ ruby -v code/hash/keys-include-vs-key.rb ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17] Calculating ------------------------------------- Hash#keys.include? 8.612k (± 2.5%) i/s - 43.248k in 5.024749s Hash#key? 6.366M (± 5.5%) i/s - 31.715M in 5.002276s Comparison: Hash#key?: 6365855.5 i/s Hash#keys.include?: 8612.4 i/s - 739.15x slower Hash#value? instead of Hash#values.include? code
Hash#values.include?allocates an array of values and performs an O(n) search;
Hash#value?performs an O(n) search without allocating a new array.
$ ruby -v code/hash/values-include-vs-value.rb ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17] Calculating ------------------------------------- Hash#values.include? 23.187k (± 4.3%) i/s - 117.720k in 5.086976s Hash#value? 38.395k (± 1.0%) i/s - 194.361k in 5.062696s Comparison: Hash#value?: 38395.0 i/s Hash#values.include?: 23186.8 i/s - 1.66x 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#update vs Hash#[]= code
$ ruby -v code/hash/update-vs-\[\]=.rb ruby 2.6.6p146 (2020-03-31 revision 67876) [x86_64-darwin18] Warming up -------------------------------------- Hash#[]= 7.453k i/100ms Hash#update 4.311k i/100ms Calculating ------------------------------------- Hash#[]= 74.764k (± 1.9%) i/s - 380.103k in 5.085962s Hash#update 43.220k (± 0.8%) i/s - 219.861k in 5.087364s Comparison: Hash#[]=: 74764.0 i/s Hash#update: 43220.1 i/s - 1.73x (± 0.00) slower Hash#merge vs Hash#**other code
$ ruby -v code/hash/merge-vs-double-splat-operator.rb ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin15] Warming up -------------------------------------- Hash#**other 64.624k i/100ms Hash#merge 38.827k i/100ms Calculating ------------------------------------- Hash#**other 798.397k (± 6.9%) i/s - 4.007M in 5.053516s Hash#merge 434.171k (± 4.5%) i/s - 2.174M in 5.018927s Comparison: Hash#**other: 798396.6 i/s Hash#merge: 434170.8 i/s - 1.84x 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 {}#merge!(Hash) vs Hash#merge({}) vs Hash#dup#merge!({}) code
When we don't want to modify the original hash, and we want duplicates to be created
See #42 for more details.
$ ruby -v code/hash/merge-bang-vs-merge-vs-dup-merge-bang.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux] Calculating ------------------------------------- {}#merge!(Hash) do end 2.006k i/100ms Hash#merge({}) 762.000 i/100ms Hash#dup#merge!({}) 736.000 i/100ms ------------------------------------------------- {}#merge!(Hash) do end 20.055k (± 2.0%) i/s - 100.300k in 5.003322s Hash#merge({}) 7.676k (± 1.2%) i/s - 38.862k in 5.063382s Hash#dup#merge!({}) 7.440k (± 1.1%) i/s - 37.536k in 5.045851s Comparison: {}#merge!(Hash) do end: 20054.8 i/s Hash#merge({}): 7676.3 i/s - 2.61x slower Hash#dup#merge!({}): 7439.9 i/s - 2.70x slower Hash#sort_by vs Hash#sort code
To sort hash by key.
$ ruby -v code/hash/hash-key-sort_by-vs-sort.rb ruby 2.2.1p85 (2015-02-26 revision 49769) [x86_64-darwin14] Calculating ------------------------------------- sort_by + to_h 11.468k i/100ms sort + to_h 8.107k i/100ms ------------------------------------------------- sort_by + to_h 122.176k (± 6.0%) i/s - 619.272k sort + to_h 81.973k (± 4.7%) i/s - 413.457k Comparison: sort_by + to_h: 122176.2 i/s sort + to_h: 81972.8 i/s - 1.49x slower Native Hash#slice vs other slice implementations before native code
Since ruby 2.5, Hash comes with a slice method to select hash members by keys.
$ ruby -v code/hash/slice-native-vs-before-native.rb ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-linux] Warming up -------------------------------------- Hash#native-slice 178.077k i/100ms Array#each 124.311k i/100ms Array#each_w/_object 110.818k i/100ms Hash#select-include 66.972k i/100ms Calculating ------------------------------------- Hash#native-slice 2.540M (± 1.5%) i/s - 12.822M in 5.049955s Array#each 1.614M (± 1.0%) i/s - 8.080M in 5.007925s Array#each_w/_object 1.353M (± 2.6%) i/s - 6.760M in 5.000441s Hash#select-include 760.944k (± 0.9%) i/s - 3.817M in 5.017123s Comparison: Hash#native-slice : 2539515.5 i/s Array#each : 1613665.5 i/s - 1.57x slower Array#each_w/_object: 1352851.8 i/s - 1.88x slower Hash#select-include : 760944.2 i/s - 3.34x 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 and block arguments vs yield code
In MRI Ruby before 2.5, block arguments are converted to Procs, which incurs a heap allocation.
$ ruby -v code/proc-and-block/proc-call-vs-yield.rb ruby 2.4.4p296 (2018-03-28 revision 63013) [x86_64-darwin18] Calculating ------------------------------------- block.call 1.967M (± 2.0%) i/s - 9.871M in 5.019328s block + yield 2.147M (± 3.3%) i/s - 10.814M in 5.044319s unused block 2.265M (± 1.9%) i/s - 11.333M in 5.004522s yield 10.436M (± 1.6%) i/s - 52.260M in 5.008851s Comparison: yield: 10436414.0 i/s unused block: 2265399.0 i/s - 4.61x slower block + yield: 2146619.0 i/s - 4.86x slower block.call: 1967300.9 i/s - 5.30x slower MRI Ruby 2.5 implements Lazy Proc allocation for block parameters, which speeds things up by about 3x.:
$ ruby -v code/proc-and-block/proc-call-vs-yield.rb ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-darwin18] Calculating ------------------------------------- block.call 1.970M (± 2.3%) i/s - 9.863M in 5.009599s block + yield 9.075M (± 2.6%) i/s - 45.510M in 5.018369s unused block 11.176M (± 2.7%) i/s - 55.977M in 5.012741s yield 10.588M (± 1.9%) i/s - 53.108M in 5.017755s Comparison: unused block: 11176355.0 i/s yield: 10588342.3 i/s - 1.06x slower block + yield: 9075355.5 i/s - 1.23x slower block.call: 1969834.0 i/s - 5.67x slower MRI Ruby 2.6 implements an optimization for block.call where a block parameter is passed:
$ ruby -v code/proc-and-block/proc-call-vs-yield.rb ruby 2.6.1p33 (2019-01-30 revision 66950) [x86_64-darwin18] Calculating ------------------------------------- block.call 10.587M (± 1.2%) i/s - 52.969M in 5.003808s block + yield 12.630M (± 0.3%) i/s - 63.415M in 5.020910s unused block 15.981M (± 0.8%) i/s - 80.255M in 5.022305s yield 15.352M (± 3.1%) i/s - 76.816M in 5.009404s Comparison: unused block: 15980789.4 i/s yield: 15351931.0 i/s - 1.04x slower block + yield: 12630378.1 i/s - 1.27x slower block.call: 10587315.1 i/s - 1.51x slower String#dup vs String#+ code
Note that String.new is not the same as the options compared, since it is always ASCII-8BIT encoded instead of the script encoding (usually UTF-8).
$ ruby -v code/string/dup-vs-unary-plus.rb ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17] Calculating ------------------------------------- String#+@ 7.697M (± 1.4%) i/s - 38.634M in 5.020313s String#dup 3.566M (± 1.0%) i/s - 17.860M in 5.008377s Comparison: String#+@: 7697108.3 i/s String#dup: 3566485.7 i/s - 2.16x slower String#casecmp vs String#casecmp? vs String#downcase + == code
String#casecmp? is available on Ruby 2.4 or later. Note that String#casecmp only works on characters A-Z/a-z, not all of Unicode.
$ ruby -v code/string/casecmp-vs-downcase-\=\=.rb ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-darwin19] Warming up -------------------------------------- String#casecmp? 395.796k i/100ms String#downcase + == 543.958k i/100ms String#casecmp 730.028k i/100ms Calculating ------------------------------------- String#casecmp? 3.687M (±10.9%) i/s - 18.602M in 5.158065s String#downcase + == 5.017M (±11.3%) i/s - 25.022M in 5.089175s String#casecmp 6.948M (± 6.0%) i/s - 35.041M in 5.062714s Comparison: String#casecmp: 6948231.0 i/s String#downcase + ==: 5017089.5 i/s - 1.38x (± 0.00) slower String#casecmp?: 3686650.7 i/s - 1.88x (± 0.00) slower String Concatenation code
$ ruby -v code/string/concatenation.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux] Warming up -------------------------------------- String#+ 149.298k i/100ms String#concat 151.505k i/100ms String#append 153.389k i/100ms "foo" "bar" 195.552k i/100ms "#{'foo'}#{'bar'}" 193.784k i/100ms Calculating ------------------------------------- String#+ 2.977M (± 1.1%) i/s - 14.930M in 5.015179s String#concat 3.017M (± 1.3%) i/s - 15.150M in 5.023063s String#append 3.076M (± 1.2%) i/s - 15.492M in 5.037683s "foo" "bar" 5.370M (± 1.0%) i/s - 26.986M in 5.026271s "#{'foo'}#{'bar'}" 5.182M (± 4.6%) i/s - 25.967M in 5.022093s Comparison: "foo" "bar": 5369594.5 i/s "#{'foo'}#{'bar'}": 5181745.7 i/s - same-ish: difference falls within error String#append: 3075719.2 i/s - 1.75x slower String#concat: 3016703.5 i/s - 1.78x slower String#+: 2977282.7 i/s - 1.80x slower String#match vs String.match? vs String#start_with?/String#end_with? code (start) code (end)
The regular expression approaches become slower as the tested string becomes longer. For short strings, String#match? performs similarly to String#start_with?/String#end_with?.
⚠️
Sometimes you cant replace regexp withstart_with?,
for example:"a\nb" =~ /^b/ #=> 2but"a\nb" =~ /\Ab/ #=> nil.
⚠️
$ ruby -v code/string/start-string-checking-match-vs-start_with.rb ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17] Calculating ------------------------------------- String#=~ 1.088M (± 4.0%) i/s - 5.471M in 5.034404s String#match? 5.138M (± 5.0%) i/s - 25.669M in 5.008810s String#start_with? 6.314M (± 4.3%) i/s - 31.554M in 5.007207s Comparison: String#start_with?: 6314182.0 i/s String#match?: 5138115.1 i/s - 1.23x slower String#=~: 1088461.5 i/s - 5.80x slower $ ruby -v code/string/end-string-checking-match-vs-end_with.rb ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17] Calculating ------------------------------------- String#=~ 918.101k (± 6.0%) i/s - 4.650M in 5.084079s String#match? 3.009M (± 6.8%) i/s - 14.991M in 5.005691s String#end_with? 4.548M (± 9.3%) i/s - 22.684M in 5.034115s Comparison: String#end_with?: 4547871.0 i/s String#match?: 3008554.5 i/s - 1.51x slower String#=~: 918100.5 i/s - 4.95x slower String#start_with? vs String#[].== code
$ ruby -v code/string/end-string-checking-match-vs-end_with.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- String#start_with? 2.047M (± 4.5%) i/s - 10.242M in 5.015146s String#[0, n] == 711.802k (± 7.3%) i/s - 3.551M in 5.019543s String#[RANGE] == 651.751k (± 6.2%) i/s - 3.296M in 5.078772s String#[0...n] == 427.207k (± 5.7%) i/s - 2.136M in 5.019245s Comparison: String#start_with?: 2046618.9 i/s String#[0, n] ==: 711802.3 i/s - 2.88x slower String#[RANGE] ==: 651751.2 i/s - 3.14x slower String#[0...n] ==: 427206.8 i/s - 4.79x slower Regexp#=== vs Regexp#match vs Regexp#match? vs String#match vs String#=~ vs String#match? code
String#match? and Regexp#match? are available on Ruby 2.4 or later. ActiveSupport provides a forward compatible extension of Regexp for older Rubies without the speed improvement.
⚠️
Sometimes you can't replacematchwithmatch?,
This is only useful for cases where you are checking
for a match and not using the resultant match object.
⚠️
Regexp#===is also faster thanString#matchbut you need to switch the order of arguments.
$ ruby -v code/string/===-vs-=~-vs-match.rb ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16] Calculating ------------------------------------- Regexp#match? 6.994M (± 3.0%) i/s - 35.144M in 5.029647s String#match? 6.909M (± 3.3%) i/s - 34.663M in 5.023177s String#=~ 2.784M (± 5.2%) i/s - 13.996M in 5.043168s Regexp#=== 2.702M (± 4.5%) i/s - 13.631M in 5.056215s Regexp#match 2.607M (± 4.9%) i/s - 13.025M in 5.009071s String#match 2.362M (± 5.7%) i/s - 11.817M in 5.020344s Comparison: Regexp#match?: 6994107.7 i/s String#match?: 6909055.7 i/s - same-ish: difference falls within error String#=~: 2783577.8 i/s - 2.51x slower Regexp#===: 2702030.0 i/s - 2.59x slower Regexp#match: 2607484.0 i/s - 2.68x slower String#match: 2362314.8 i/s - 2.96x slower See #59 and #62 for discussions.
String#gsub vs String#sub vs String#[]= code
$ ruby -v code/string/gsub-vs-sub.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux] Warming up -------------------------------------- String#gsub 48.360k i/100ms String#sub 45.739k i/100ms String#dup["string"]= 59.896k i/100ms Calculating ------------------------------------- String#gsub 647.666k (± 3.3%) i/s - 3.240M in 5.008504s String#sub 756.665k (± 2.0%) i/s - 3.796M in 5.019235s String#dup["string"]= 917.873k (± 1.8%) i/s - 4.612M in 5.026253s Comparison: String#dup["string"]=: 917873.1 i/s String#sub: 756664.7 i/s - 1.21x slower String#gsub: 647665.6 i/s - 1.42x 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 String#gsub vs String#tr vs String#delete code
ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux] Calculating ------------------------------------- String#gsub 1.342M (± 1.3%) i/s - 6.816M in 5.079675s String#tr 2.627M (± 1.0%) i/s - 13.387M in 5.096083s String#delete 2.924M (± 0.7%) i/s - 14.889M in 5.093070s String#delete const 3.136M (± 2.6%) i/s - 15.866M in 5.064043s Comparison: String#delete const: 3135559.1 i/s String#delete: 2923531.8 i/s - 1.07x slower String#tr: 2627150.5 i/s - 1.19x slower String#gsub: 1342013.4 i/s - 2.34x slower Mutable vs Immutable code
$ ruby -v code/string/mutable_vs_immutable_strings.rb ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin14] Calculating ------------------------------------- Without Freeze 7.279M (± 6.6%) i/s - 36.451M in 5.029785s With Freeze 9.329M (± 7.9%) i/s - 46.370M in 5.001345s Comparison: With Freeze: 9329054.3 i/s Without Freeze: 7279203.1 i/s - 1.28x slower String#sub! vs String#gsub! vs String#[]= code
Note that String#[] will throw an IndexError when given string or regexp not matched.
$ ruby -v code/string/sub\!-vs-gsub\!-vs-\[\]\=.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- String#['string']= 74.512k i/100ms String#sub!'string' 52.801k i/100ms String#gsub!'string' 34.480k i/100ms String#[/regexp/]= 55.325k i/100ms String#sub!/regexp/ 45.770k i/100ms String#gsub!/regexp/ 27.665k i/100ms ------------------------------------------------- String#['string']= 1.215M (± 6.2%) i/s - 6.110M String#sub!'string' 752.731k (± 6.2%) i/s - 3.749M String#gsub!'string' 481.183k (± 4.4%) i/s - 2.414M String#[/regexp/]= 840.615k (± 5.3%) i/s - 4.205M String#sub!/regexp/ 663.075k (± 7.8%) i/s - 3.295M String#gsub!/regexp/ 342.004k (± 7.5%) i/s - 1.715M Comparison: String#['string']=: 1214845.5 i/s String#[/regexp/]=: 840615.2 i/s - 1.45x slower String#sub!'string': 752731.4 i/s - 1.61x slower String#sub!/regexp/: 663075.3 i/s - 1.83x slower String#gsub!'string': 481183.5 i/s - 2.52x slower String#gsub!/regexp/: 342003.8 i/s - 3.55x slower String#sub vs String#delete_prefix code
Ruby 2.5 introduced String#delete_prefix. Note that this can only be used for removing characters from the start of a string.
$ ruby -v code/string/sub-vs-delete_prefix.rb ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17] Calculating ------------------------------------- String#delete_prefix 4.112M (± 1.8%) i/s - 20.707M in 5.037928s String#sub 814.725k (± 1.4%) i/s - 4.088M in 5.018962s Comparison: String#delete_prefix: 4111531.1 i/s String#sub: 814725.3 i/s - 5.05x slower String#sub vs String#delete_prefix vs String#[] code
Ruby 2.5 introduced String#delete_prefix. Note that this can only be used for removing characters from the start of a string, and String#[Range] is only applicable when it's known the substring is at the start, and the substring's length is known.
$ ruby -v ../fast-ruby/code/string/sub-vs-delete_prefix-vs-substring.rb ruby 3.2.3 (2024-01-18 revision 52bb2ac0a6) [x86_64-linux-gnu] Calculating ------------------------------------- String#[Range] 4.494M (± 4.7%) i/s (222.53 ns/i) - 22.775M in 5.080785s String#delete_prefix 3.980M (± 6.2%) i/s (251.27 ns/i) - 20.072M in 5.067337s String#[Regexp] 1.371M (± 5.7%) i/s (729.45 ns/i) - 6.898M in 5.050030s String#sub 1.184M (± 6.3%) i/s (844.85 ns/i) - 5.936M in 5.040405s Comparison: String#[Range]: 4493765.8 i/s String#delete_prefix: 3979705.8 i/s - 1.13x slower String#[Regexp]: 1370898.6 i/s - 3.28x slower String#sub: 1183638.7 i/s - 3.80x slower String#sub vs String#chomp vs String#delete_suffix code
Ruby 2.5 introduced String#delete_suffix as a counterpart to delete_prefix. The performance gain over chomp is small and during some runs the difference falls within the error margin. Note that this can only be used for removing characters from the end of a string.
$ ruby -v code/string/sub-vs-chomp-vs-delete_suffix.rb ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17] Calculating ------------------------------------- String#sub 838.415k (± 1.7%) i/s - 4.214M in 5.027412s String#chomp 3.951M (± 2.1%) i/s - 19.813M in 5.017089s String#delete_suffix 4.202M (± 2.1%) i/s - 21.075M in 5.017429s Comparison: String#delete_suffix: 4202201.7 i/s String#chomp: 3950921.9 i/s - 1.06x slower String#sub: 838415.3 i/s - 5.01x slower String#unpack1 vs String#unpack[0] code
Ruby 2.4.0 introduced unpack1 to skip creating the intermediate array object.
$ ruby -v code/string/unpack1-vs-unpack\[0\].rb ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17] Warming up -------------------------------------- String#unpack1 224.291k i/100ms String#unpack[0] 201.870k i/100ms Calculating ------------------------------------- String#unpack1 4.864M (± 4.2%) i/s - 24.448M in 5.035203s String#unpack[0] 3.778M (± 4.0%) i/s - 18.976M in 5.031253s Comparison: String#unpack1: 4864467.2 i/s String#unpack[0]: 3777815.6 i/s - 1.29x slower Remove extra spaces (or other contiguous characters) code
The code is tested against contiguous spaces but should work for other chars too.
$ ruby -v code/string/remove-extra-spaces-or-other-chars.rb ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux] Warming up -------------------------------------- String#gsub/regex+/ 1.644k i/100ms String#squeeze 24.681k i/100ms Calculating ------------------------------------- String#gsub/regex+/ 14.668k (± 5.1%) i/s - 73.980k in 5.056887s String#squeeze 372.910k (± 8.4%) i/s - 1.851M in 5.011881s Comparison: String#squeeze: 372910.3 i/s String#gsub/regex+/: 14668.1 i/s - 25.42x slower Time.iso8601 vs Time.parse code
When expecting well-formatted data from e.g. an API, iso8601 is faster and will raise an ArgumentError on malformed input.
$ ruby -v code/time/iso8601-vs-parse.rb ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17] Warming up -------------------------------------- Time.iso8601 10.234k i/100ms Time.parse 4.228k i/100ms Calculating ------------------------------------- Time.iso8601 114.485k (± 3.5%) i/s - 573.104k in 5.012008s Time.parse 43.711k (± 4.1%) i/s - 219.856k in 5.038349s Comparison: Time.iso8601: 114485.1 i/s Time.parse: 43710.9 i/s - 2.62x slower cover? vs include? code
cover? only check if it is within the start and end, include? needs to traverse the whole range.
$ ruby -v code/range/cover-vs-include.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-linux] Calculating ------------------------------------- range#cover? 85.467k i/100ms range#include? 7.720k i/100ms range#member? 7.783k i/100ms plain compare 102.189k i/100ms ------------------------------------------------- range#cover? 1.816M (± 5.6%) i/s - 9.060M range#include? 83.344k (± 5.0%) i/s - 416.880k range#member? 82.654k (± 5.0%) i/s - 412.499k plain compare 2.581M (± 6.2%) i/s - 12.876M Comparison: plain compare: 2581211.8 i/s range#cover?: 1816038.5 i/s - 1.42x slower range#include?: 83343.9 i/s - 30.97x slower range#member?: 82654.1 i/s - 31.23x 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
-
Go faster, off the Rails - Benchmarks for your whole Rails app
-
Talk by Davy Stevenson @ RubyConf 2014.
-
Provides Big O notation benchmarking for Ruby.
-
Talk by Prem Sichanugrist @ Ruby Kaigi 2014.
-
Make your Rubies go faster with this command line tool.
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
To the extent possible under law, @JuanitoFatas has waived all copyright and related or neighboring rights to "fast-ruby".
This work belongs to the community.