I18nTestRepro

This repo exists to show how I18n.locale can leak between requests via the usage of Thread Local Storage(TLS), a.k.a Thread.current.

To replicate, have two tabs open (this may take a few retries)

• bundle install
• rails s (This application runs Puma with max 5 threads.)
• On one tab open (Tab1) open http://localhost:3000?locale=es
  • Only MainController#index sets I18n.locale to params[:locale] if present one or I18n.default_locale
• On another tab (Tab2) open http://localhost:3000/foo
  • This controller action is not tampering with I18n.locale and expects it to return en (the default locale)
• Now, try to refresh both tabs as simultaneously/quickly as possible (simulating a high concurrency env).
• Eventually notice, on Tab2 the current locale being rendered is no longer en but es

Here is a screen capture demonstrating the above: https://www.dropbox.com/s/zbogg3vag5at98b/i18n-locale-leak.mov?dl=0