What is the difference between Rails.cache.clear and rake tmp:cache:clear?

rake, ruby-on-rails, ruby-on-rails-3, ruby-on-rails-3.2

Solution

The rake task only clears out files that are stored on the filesystem in `"#{Rails.root}/tmp/cache"`. Here's the code for that task.

namespace :cache do
  # desc "Clears all files and directories in tmp/cache"
  task :clear do
    FileUtils.rm_rf(Dir['tmp/cache/[^.]*'])
  end
end

https://github.com/rails/rails/blob/ef5d85709d346e55827e88f53430a2cbe1e5fb9e/railties/lib/rails/tasks/tmp.rake#L25-L30

`Rails.cache.clear` will do different things depending on your apps setting for `config.cache_store`. http://guides.rubyonrails.org/caching_with_rails.html#cache-stores

If you are using `config.cache_store = :file_store` then `Rails.cache.clear` will be functionally identical to `rake tmp:cache:clear`. However, if you're using some other `cache_store`, like `:memory_store` or `:mem_cache_store`, then only `Rails.cache.clear` will clear your app cache. In that case `rake tmp:cache:clear` will just try to remove files from `"#{Rails.root}/tmp/cache"` but probably won't actually do anything since nothing is probably being cached on the filesystem.

Problem

Original source