require() bombed my multi-threaded app!

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jonathan martin

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@nybblr

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Atlanta GA, USA

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#ruby #autoload

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#1. Plain ol’ Ruby eval, load, & require.

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Cookery.rb

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/home/nybblr/ !"" cookery # !"" ingredient.rb # $"" recipe.rb !"" cookery.rb $"" main.rb 1 directory, 4 files > tree /home/nybblr

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puts to_s > main self.puts self.to_s > main > irb

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puts self.class.ancestors > [Object, Kernel, BasicObject] self.eval "puts to_s" > main > irb

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class Cook def get_binding binding end end eval "puts to_s", Cook.new.get_binding > # > irb

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puts "Loaded Cookery::Recipe class!" module Cookery class Recipe end end cookery/recipe.rb

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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

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load File.join(dir, "cookery/recipe.rb") > Loaded Cookery::Recipe class! main.rb

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$LOAD_PATH.unshift(dir) load "cookery/recipe.rb" > Loaded Cookery::Recipe class! main.rb

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$LOAD_PATH.unshift(dir) require "cookery/recipe" > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery/recipe.rb" main.rb

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require File.join(dir, "cookery/recipe.rb") > Loaded Cookery::Recipe class! require "cookery/recipe" > *Eerie silence…* main.rb

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# 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

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#2. Autoloading with ActiveSupport

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# 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

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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

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module Cookery extend ActiveSupport::Autoload autoload :Recipe end cookery.rb

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require 'cookery' Cookery::Recipe > Loaded Cookery::Recipe class! p $LOADED_FEATURES.last > "/home/nybblr/cookery/recipe.rb" require 'cookery/recipe' > *Eerie silence…* main.rb

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#3. Namespaces matter to Autoload.

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puts "Loaded ::Recipe class!" class Recipe end cookery/recipe.rb

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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

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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

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#4. Constants should not be redeﬁned.

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puts "Loaded Cookery::Recipe class!" module Cookery class Recipe CONSTANT = "constant".freeze end end cookery/recipe.rb

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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

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#5. Circular Deps require + autoload = ﬁsts

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puts "Loaded Cookery::Recipe class!" module Cookery class Recipe CONSTANT = Ingredient end end cookery/recipe.rb

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puts "Loaded Cookery::Ingredient class!" require 'cookery/recipe' module Cookery class Ingredient CONSTANT = Recipe end end cookery/ingredient.rb

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# 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

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ActiveSupport::Dependencies.mechanism = :require ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! > Loaded Cookery::Ingredient class! main.rb

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puts "Loaded Cookery::Ingredient class!" # require 'cookery/recipe' module Cookery class Ingredient CONSTANT = Recipe end end cookery/ingredient.rb

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# ActiveSupport::Dependencies.mechanism = :load ActiveSupport::Dependencies.autoload_paths << ROOT Cookery::Recipe > Loaded Cookery::Recipe class! > Loaded Cookery::Ingredient class! main.rb

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#6. eagerload_paths !== autoload_paths.

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module Cookery class Application < Rails::Application config.autoload_paths << "#{config.root}/lib" end end config/application.rb

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module Cookery class Application < Rails::Application config.eager_load_paths << "#{config.root}/lib" end end config/application.rb

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module Cookery class Application < Rails::Application config.eager_load_paths += ["#{config.root}/app/models", "#{config.root}/app/models/queries"] end end config/application.rb

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#7. Isolated Tests use a diﬀerent spec helper.

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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

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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

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require 'spec_helper' describe Cookery::Recipe do # That was fast! end spec/cookery/recipe_spec.rb