require() bombed my multi-threaded app!

Would you like Circular Dependencies with that? In Rails we take autoloading for granted, but slow test suites and evasive multi-thread bombs too often drive us to upbraid ActiveSupport’s autoloading magic.

To dispel the magic, we will cover nothing less than the entirety of require’s modest origins, the enlightening truth of Ruby execution, a selection of minimal autoload examples, the most interesting ways to break integration specs, and utopian isolation practices. All while speeding up your test suite.

https://github.com/nybblr/ruby-code-loading

Transcript

1. require() bombed my multi-threaded app!
2. jonathan martin
3. @nybblr
4. Atlanta GA, USA
12. #ruby #autoload
19. #1. Plain ol’ Ruby eval, load, & require.
20. Cookery.rb
21. /home/nybblr/ !"" cookery # !"" ingredient.rb # $"" recipe.rb !"" cookery.rb $"" main.rb 1 directory, 4 files > tree /home/nybblr
22. puts to_s > main self.puts self.to_s > main > irb
23. puts self.class.ancestors > [Object, Kernel, BasicObject] self.eval "puts to_s" > main > irb
24. class Cook def get_binding binding end end eval "puts to_s", Cook.new.get_binding > #<Cook:0x007f88918e3110> > irb
25. puts "Loaded Cookery::Recipe class!" module Cookery class Recipe end end cookery/recipe.rb
26. dir = File.expand_path("..", __FILE__) file = File.join(dir, "cookery/recipe.rb") eval File.read(file), binding, "cookery/recipe.rb", 1 > Loaded Cookery::Recipe class! main.rb
27. load File.join(dir, "cookery/recipe.rb") > Loaded Cookery::Recipe class! main.rb
28. $LOAD_PATH.unshift(dir) load "cookery/recipe.rb" > Loaded Cookery::Recipe class! main.rb
29. $LOAD_PATH.unshift(dir) require "cookery/recipe" > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery/recipe.rb" main.rb
30. require File.join(dir, "cookery/recipe.rb") > Loaded Cookery::Recipe class! require "cookery/recipe" > *Eerie silence…* main.rb
31. # main.rb header from now on! require 'active_support' ROOT = File.expand_path("..", __FILE__) $LOAD_PATH.unshift(ROOT) p $LOADED_FEATURES.last > ".../active_support/dependencies.rb" main.rb
32. #2. Autoloading with ActiveSupport
33. # ActiveSupport::Dependencies.mechanism = :load ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > ".../active_support/dependencies.rb" require 'cookery/recipe' > Loaded Cookery::Recipe class! main.rb
34. ActiveSupport::Dependencies.mechanism = :require ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery/recipe.rb" require 'cookery/recipe' > *Eerie silence…* main.rb
35. module Cookery extend ActiveSupport::Autoload autoload :Recipe end cookery.rb
36. require 'cookery' Cookery::Recipe > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery/recipe.rb" require 'cookery/recipe' > *Eerie silence…* main.rb
37. #3. Namespaces matter to Autoload.
38. puts "Loaded ::Recipe class!" class Recipe end cookery/recipe.rb
39. ActiveSupport::Dependencies.mechanism = :require ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded ::Recipe class! > Unable to autoload constant Cookery::Recipe, expected ./cookery/recipe.rb to define it (LoadError) main.rb
40. ActiveSupport::Dependencies.mechanism = :require ActiveSupport::Dependencies.autoload_paths += ["#{ROOT}/cookery", ROOT] Recipe > Loaded ::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery/recipe.rb" Cookery::Recipe > Unable to autoload constant Cookery::Recipe, expected ./cookery/ recipe.rb to define it (LoadError) main.rb
41. #4. Constants should not be redefined.
42. puts "Loaded Cookery::Recipe class!" module Cookery class Recipe CONSTANT = "constant".freeze end end cookery/recipe.rb
43. # ActiveSupport::Dependencies.mechanism = :load ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > ".../active_support/dependencies.rb" require 'cookery/recipe' > Loaded Cookery::Recipe class! > already initialized constant Cookery::Recipe::CONSTANT main.rb
44. ActiveSupport::Dependencies.mechanism = :require ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery.rb" require 'cookery/recipe' > *Eerie silence...* main.rb
45. #5. Circular Deps require + autoload = fists
46. puts "Loaded Cookery::Recipe class!" module Cookery class Recipe CONSTANT = Ingredient end end cookery/recipe.rb
47. puts "Loaded Cookery::Ingredient class!" require 'cookery/recipe' module Cookery class Ingredient CONSTANT = Recipe end end cookery/ingredient.rb
48. # ActiveSupport::Dependencies.mechanism = :load ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! > Loaded Cookery::Ingredient class! > Loaded Cookery::Recipe class! > Circular dependency detected while autoloading constant Cookery::Ingredient (RuntimeError) main.rb
49. ActiveSupport::Dependencies.mechanism = :require ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! > Loaded Cookery::Ingredient class! main.rb
50. puts "Loaded Cookery::Ingredient class!" # require 'cookery/recipe' module Cookery class Ingredient CONSTANT = Recipe end end cookery/ingredient.rb
51. # ActiveSupport::Dependencies.mechanism = :load ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! > Loaded Cookery::Ingredient class! main.rb
52. #6. eagerload_paths !== autoload_paths.
53. module Cookery class Application < Rails::Application config.autoload_paths << "#{config.root}/lib" end end config/application.rb
54. module Cookery class Application < Rails::Application config.eager_load_paths << "#{config.root}/lib" end end config/application.rb
55. module Cookery class Application < Rails::Application config.eager_load_paths += ["#{config.root}/app/models", "#{config.root}/app/models/queries"] end end config/application.rb
56. #7. Isolated Tests use a different spec helper.
57. ENV["RAILS_ENV"] ||= 'test' if !Object.const_defined?(:Rails) require 'active_support/all' root = File.expand_path('../..', __FILE__) ActiveSupport::Dependencies.autoload_paths += Dir["#{root}/app/*/"] end # General config RSpec.configure do |config| config.order = :random end spec/spec_helper.rb
58. require File.expand_path('../../config/environment', __FILE__) require 'spec_helper' require 'rspec/rails' # Rails specific config RSpec.configure do |config| config.use_transactional_fixtures = true config.infer_spec_type_from_file_location! end spec/rails_helper.rb
59. require 'spec_helper' describe Cookery::Recipe do # That was fast! end spec/cookery/recipe_spec.rb
61. AS::Dep.mechanism = :require
62. autoload + require( ) =
63. CONSTANT ||= “string”.freeze
64. autoload_paths <=> AS::Autoload
65. spec_helper.rb > rails_helper.rb
66. require_dependency( ) =
67. bit.ly/lol-ruby
68. questions? domande?
69. thanks! @nybblr