Veryfing "Table 1—Number of additional T_NODE objects created by an iterator" from "Ruby Performance Optimization" book

how_many_nodes.rb

def count_nodes(label)
  before = ObjectSpace.count_objects
  yield
  after = ObjectSpace.count_objects

  puts "  #{label} created T_NODE: %d" % (after[:T_NODE] - before[:T_NODE])
end

class MyClass
  include Enumerable

  def each
    yield 1
    yield 2
    yield 3
  end
end

GC.disable

puts "RUBY_VERSION: #{RUBY_VERSION}"

def measure(title, enum)
  puts "------ Measuring #{title} -----"

  count_nodes("#all?")             { enum.dup.all?                  { |e| e > 1 } }
  count_nodes("#any?")             { enum.dup.any?                  { |e| e > 1 } }
  count_nodes("#collect")          { enum.dup.collect               { |e| e * 2 } }
  count_nodes("#cycle")            { enum.dup.cycle(2).to_a }
  count_nodes("#delete_if")        { enum.dup.delete_if             { |e| e > 1 } } if enum.respond_to?(:delete_if)
  count_nodes("#detect")           { enum.dup.detect                { |e| e > 1 } }
  count_nodes("#each")             { enum.dup.each                  { |e| e + 1 } }
  count_nodes("#each_index")       { enum.dup.each_index            { |e| e + 1 } } if enum.respond_to?(:each_index)
  count_nodes("#each_with_index")  { enum.dup.each_with_index       { |e, i| e + i } }
  count_nodes("#each_with_object") { enum.dup.each_with_object(123) { |e, o| e + o } }
  count_nodes("#fill")             { enum.dup.fill                  { "x" } } if enum.respond_to?(:fill)
  count_nodes("#find")             { enum.dup.find                  { |e| e > 1 } }
  count_nodes("#find_all")         { enum.dup.find_all              { |e| e > 1 } }
  count_nodes("#grep")             { enum.dup.grep(/\d/) }
  count_nodes("#inject")           { enum.dup.inject(0)             { |sum, e| sum + e } }
  count_nodes("#map")              { enum.dup.map                   { |e| e * 2 } }
  count_nodes("#none?")            { enum.dup.none?                 { |e| e > 1 } }
  count_nodes("#one?")             { enum.dup.one?                  { |e| e > 1 } }
  count_nodes("#reduce")           { enum.dup.reduce(0)             { |sum, e| sum + e } }
  count_nodes("#reject")           { enum.dup.reject                { |e| e > 1 } }
  count_nodes("#reverse_each")     { enum.dup.reverse_each          { |e| e + 1 } }
  count_nodes("#select")           { enum.dup.select                { |e| e > 1 } }

  puts "\n\n"
end

measure("Array", [1, 2, 3])
measure("MyClass (Enumerable)", MyClass.new)

results.txt

RUBY_VERSION: 2.1.5
------ Measuring Array -----
  #all? created T_NODE: 3
  #any? created T_NODE: 3
  #collect created T_NODE: 0
  #cycle created T_NODE: 2
  #delete_if created T_NODE: 0
  #detect created T_NODE: 3
  #each created T_NODE: 0
  #each_index created T_NODE: 0
  #each_with_index created T_NODE: 2
  #each_with_object created T_NODE: 1
  #fill created T_NODE: 0
  #find created T_NODE: 3
  #find_all created T_NODE: 1
  #grep created T_NODE: 3
  #inject created T_NODE: 2
  #map created T_NODE: 0
  #none? created T_NODE: 3
  #one? created T_NODE: 3
  #reduce created T_NODE: 2
  #reject created T_NODE: 0
  #reverse_each created T_NODE: 0
  #select created T_NODE: 0


------ Measuring MyClass (Enumerable) -----
  #all? created T_NODE: 3
  #any? created T_NODE: 3
  #collect created T_NODE: 1
  #cycle created T_NODE: 3
  #detect created T_NODE: 3
  #each created T_NODE: 0
  #each_with_index created T_NODE: 2
  #each_with_object created T_NODE: 1
  #find created T_NODE: 3
  #find_all created T_NODE: 1
  #grep created T_NODE: 3
  #inject created T_NODE: 2
  #map created T_NODE: 1
  #none? created T_NODE: 3
  #one? created T_NODE: 3
  #reduce created T_NODE: 2
  #reject created T_NODE: 1
  #reverse_each created T_NODE: 1
  #select created T_NODE: 1




RUBY_VERSION: 2.2.4
------ Measuring Array -----
  #all? created T_NODE: 3
  #any? created T_NODE: 0
  #collect created T_NODE: 0
  #cycle created T_NODE: 2
  #delete_if created T_NODE: 0
  #detect created T_NODE: 3
  #each created T_NODE: 0
  #each_index created T_NODE: 0
  #each_with_index created T_NODE: 2
  #each_with_object created T_NODE: 1
  #fill created T_NODE: 0
  #find created T_NODE: 3
  #find_all created T_NODE: 1
  #grep created T_NODE: 3
  #inject created T_NODE: 2
  #map created T_NODE: 0
  #none? created T_NODE: 3
  #one? created T_NODE: 3
  #reduce created T_NODE: 2
  #reject created T_NODE: 0
  #reverse_each created T_NODE: 0
  #select created T_NODE: 0


------ Measuring MyClass (Enumerable) -----
  #all? created T_NODE: 3
  #any? created T_NODE: 3
  #collect created T_NODE: 1
  #cycle created T_NODE: 3
  #detect created T_NODE: 3
  #each created T_NODE: 0
  #each_with_index created T_NODE: 2
  #each_with_object created T_NODE: 1
  #find created T_NODE: 3
  #find_all created T_NODE: 1
  #grep created T_NODE: 3
  #inject created T_NODE: 2
  #map created T_NODE: 1
  #none? created T_NODE: 3
  #one? created T_NODE: 3
  #reduce created T_NODE: 2
  #reject created T_NODE: 1
  #reverse_each created T_NODE: 1
  #select created T_NODE: 1



RUBY_VERSION: 2.3.0
------ Measuring Array -----
  #all? created T_NODE: 0
  #any? created T_NODE: 0
  #collect created T_NODE: 0
  #cycle created T_NODE: 0
  #delete_if created T_NODE: 0
  #detect created T_NODE: 0
  #each created T_NODE: 0
  #each_index created T_NODE: 0
  #each_with_index created T_NODE: 0
  #each_with_object created T_NODE: 0
  #fill created T_NODE: 0
  #find created T_NODE: 0
  #find_all created T_NODE: 0
  #grep created T_NODE: 0
  #inject created T_NODE: 0
  #map created T_NODE: 0
  #none? created T_NODE: 0
  #one? created T_NODE: 0
  #reduce created T_NODE: 0
  #reject created T_NODE: 0
  #reverse_each created T_NODE: 0
  #select created T_NODE: 0


------ Measuring MyClass (Enumerable) -----
  #all? created T_NODE: 0
  #any? created T_NODE: 0
  #collect created T_NODE: 0
  #cycle created T_NODE: 0
  #detect created T_NODE: 0
  #each created T_NODE: 0
  #each_with_index created T_NODE: 0
  #each_with_object created T_NODE: 0
  #find created T_NODE: 0
  #find_all created T_NODE: 0
  #grep created T_NODE: 0
  #inject created T_NODE: 0
  #map created T_NODE: 0
  #none? created T_NODE: 0
  #one? created T_NODE: 0
  #reduce created T_NODE: 0
  #reject created T_NODE: 0
  #reverse_each created T_NODE: 0
  #select created T_NODE: 0