const_missing with config.threadsafe!

[durandom]

In production I have config.threadsafe! enabled.
This leads to models not accesible in SitemapGenerator:

SitemapGenerator::Sitemap.add_links do |sitemap|
  Monster.where(:weight => weight).find_each do |m|
    sitemap.add m.path.to_s, :changefreq => 'monthly', :lastmod => m.updated_at, :priority => priority
  end
end

produces

bundle exec rake --trace sitemap:refresh CONFIG_FILE="config/sitemap_monsters.rb" 
** Invoke sitemap:refresh (first_time)
** Invoke sitemap:create (first_time)
** Invoke sitemap:require_environment (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute sitemap:require_environment
** Execute sitemap:create
rake aborted!
uninitialized constant Monster
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/ext/module.rb:36:in `const_missing'
config/sitemap_monsters.rb:26:in `block in run'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/lib/sitemap_generator/interpreter.rb:47:in `eval'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/lib/sitemap_generator/link_set.rb:33:in `create'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/lib/sitemap_generator/link_set.rb:43:in `add_links'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/lib/sitemap_generator.rb:27:in `method_missing'
config/sitemap_monsters.rb:8:in `run'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/lib/sitemap_generator/interpreter.rb:65:in `instance_eval'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/lib/sitemap_generator/interpreter.rb:65:in `run'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/sitemap_generator-2.0.1/tasks/sitemap_generator_tasks.rake:41:in `block (2 levels) in <top (required)>'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:205:in `call'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:205:in `block in execute'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:200:in `each'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:200:in `execute'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:158:in `block in invoke_with_call_chain'
/usr/local/rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:176:in `block in invoke_prerequisites'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:174:in `each'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:174:in `invoke_prerequisites'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:157:in `block in invoke_with_call_chain'
/usr/local/rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/task.rb:144:in `invoke'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:112:in `invoke_task'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:90:in `block (2 levels) in top_level'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:90:in `each'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:90:in `block in top_level'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:129:in `standard_exception_handling'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:84:in `top_level'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:62:in `block in run'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:129:in `standard_exception_handling'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/lib/rake/application.rb:59:in `run'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/gems/rake-0.9.2/bin/rake:32:in `<top (required)>'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/bin/rake:19:in `load'
/srv/monsterzoo/shared/bundle/ruby/1.9.1/bin/rake:19:in `<main>'
Tasks: TOP => sitemap:refresh => sitemap:create

The only workaround is to disable threadsafety for rake tasks in my environment:

config.threadsafe! unless $rails_rake_task

[kjvarga]

Hi @durandom,

I'm afraid this is a general Rails issue with class loading and threadsafe. Check out these threads:

http://groups.google.com/group/rubyonrails-core/browse_thread/thread/b13dbe0b8f12b7dc
http://www.multunus.com/2010/11/rails-threadsafe-and-rake-task/

Cheers,