Benchmark between `Array#|` and `#uniq`

benchmark.md

# frozen_string_literal: true

require 'bundler/setup'
Bundler.setup :system

require 'pry-byebug'

require 'benchmark'
require 'benchmark/ips'
require 'benchmark/memory'


puts '```ruby'
puts File.read(__FILE__).gsub("\t", '  ')
puts '```'
puts
puts '### Output'
puts
puts '```'


ARRAY = %w[1 1 2 3 4 4 4].freeze


def via_union
  ARRAY | []
end

def via_uniq
  ARRAY.uniq
end


def test
  results = %i[
    via_union
    via_uniq
  ].each_with_object([]) do |method_name, array|
    array << (result = send method_name)
    puts "Result of #{method_name}:"
    pp result
    puts
  end
  uniq_size = results.uniq.size
  puts "Uniq results: #{uniq_size}"
  puts
  exit 1 if uniq_size > 1
end

test

Benchmark.ips do |x|
  x.report('via_union') { via_union }
  x.report('via_uniq') { via_uniq }

  x.compare!
end

Benchmark.memory do |x|
  x.report('via_union') { 100.times { via_union } }
  x.report('via_uniq') { 100.times { via_uniq } }

  x.compare!
end


puts '```'

Output

Result of via_union:
["1", "2", "3", "4"]

Result of via_uniq:
["1", "2", "3", "4"]

Uniq results: 1

Warming up --------------------------------------
           via_union   229.711k i/100ms
            via_uniq   364.966k i/100ms
Calculating -------------------------------------
           via_union      2.308M (± 1.2%) i/s -     11.715M in   5.077271s
            via_uniq      3.582M (± 1.3%) i/s -     18.248M in   5.095760s

Comparison:
            via_uniq:  3581676.4 i/s
           via_union:  2307703.0 i/s - 1.55x  (± 0.00) slower

Calculating -------------------------------------
           via_union    24.000k memsize (     0.000  retained)
                       200.000  objects (     0.000  retained)
                         0.000  strings (     0.000  retained)
            via_uniq     7.200k memsize (     0.000  retained)
                       100.000  objects (     0.000  retained)
                         0.000  strings (     0.000  retained)

Comparison:
            via_uniq:       7200 allocated
           via_union:      24000 allocated - 3.33x more