today's bench

hash-find-max-bench.rb

require 'benchmark'
require 'active_support/all'

n = 20000
m = 100

arr = Array.new(m){|i| [i, [:a, :b, :c, :d].sample] }.shuffle.to_h
Benchmark.bmbm do |b|
  b.report("1:") { n.times{ arr.select{|_,v| v == :a }.max&.first }}
  b.report("2:") { n.times{ arr.each_with_object([]){|(k,v),o| o << k if v == :a }.max }}
  b.report("3:") { n.times{ a = 0; arr.each{|k,v| a = k if v == :a && a < k }; a }}
end

#          user     system      total        real
# 1:   0.380000   0.000000   0.380000 (  0.390095)
# 2:   0.310000   0.000000   0.310000 (  0.323532)
# 3:   0.150000   0.000000   0.150000 (  0.152381)