autoload.rb

# Benchmark performance differences between "require" and "Autoload"
#
# $ for run in {1..3}; do ZEITWERK=0 AUTOLOAD=0 ruby scripts/autoload.rb && ZEITWERK=0 AUTOLOAD=1 ruby scripts/autoload.rb; done
# REQUIRE  0.208000   0.360310   0.568310 (  0.568952)
# AUTOLOAD  0.242265   0.374332   0.616597 (  0.617540)
# REQUIRE  0.214861   0.360820   0.575681 (  0.576603)
# AUTOLOAD  0.225601   0.364912   0.590513 (  0.590673)
# REQUIRE  0.214296   0.359103   0.573399 (  0.574008)
# AUTOLOAD  0.224972   0.359481   0.584453 (  0.584926)
# $ for run in {1..3}; do ZEITWERK=1 AUTOLOAD=0 ruby scripts/autoload.rb && ZEITWERK=1 AUTOLOAD=1 ruby scripts/autoload.rb; done
# REQUIRE(Z)  0.240464   0.364613   0.605077 (  0.605292)
# AUTOLOAD(Z)  0.280514   0.380929   0.661443 (  0.671503)
# REQUIRE(Z)  0.251022   0.377413   0.628435 (  0.631271)
# AUTOLOAD(Z)  0.271090   0.376573   0.647663 (  0.656937)
# REQUIRE(Z)  0.250157   0.375761   0.625918 (  0.629233)
# AUTOLOAD(Z)  0.272919   0.377538   0.650457 (  0.651376)

require 'benchmark'
require "tmpdir"

CONST_COUNT = 10_000

tmpdir = Dir.mktmpdir

const_names = []
CONST_COUNT.times do |n|
  const_name = :"M#{n}"

  File.write(tmpdir + "/#{const_name}.rb", <<~RUBY)
    module Namespace
      module #{const_name}
        def self.property=(value)
          @property = value
        end
      end
    end
  RUBY

  const_names << const_name
end

File.write(tmpdir + "/namespace_require.rb", <<~RUBY)
  #{const_names.map { |const_name| "require '#{tmpdir}/#{const_name}.rb'" }.join("\n")}

  module Namespace
  end

  #{const_names.map { |const_name| "Namespace::#{const_name}.property = true" }.join("\n")}
RUBY

File.write(tmpdir + "/namespace_autoload.rb", <<~RUBY)
  module Namespace
    #{const_names.map { |const_name| "autoload :#{const_name}, '#{tmpdir}/#{const_name}.rb'" }.join("\n")}
  end

  #{const_names.map { |const_name| "Namespace::#{const_name}.property = true" }.join("\n")}
RUBY


AUTOLOAD = ENV["AUTOLOAD"] == "1"
ZEITWERK = ENV["ZEITWERK"] == "1"

if ZEITWERK
  require 'bundler/inline'
  gemfile do
    source 'https://rubygems.org'
    gem 'zeitwerk'
  end

  Zeitwerk::Loader.new.setup
end

if AUTOLOAD
  puts "AUTOLOAD#{ZEITWERK ? "(Z)" : ""}" + Benchmark.measure { require tmpdir + "/namespace_autoload.rb" }.to_s
else
  puts "REQUIRE#{ZEITWERK ? "(Z)" : ""}" + Benchmark.measure { require tmpdir + "/namespace_require.rb" }.to_s
end