Question

I’m working on some middleware for rails, working with a pretty recent version:

pfernand-2-mn:~ pfernand$ rails -v
Rails 3.1.2

This is the output of rake middleware:

use ActionDispatch::Static
** use Rack::Lock **
use ActiveSupport::Cache::Strategy::LocalCache
use Rack::Runtime
use Rails::Rack::Logger
use ActionDispatch::ShowExceptions
use ActionDispatch::RemoteIp
use Rack::Sendfile
use ActionDispatch::Callbacks
use ActiveRecord::ConnectionAdapters::ConnectionManagement
use ActiveRecord::QueryCache
use ActionDispatch::Cookies
use ActionDispatch::Session::CookieStore
use ActionDispatch::Flash
use ActionDispatch::ParamsParser
use Rack::MethodOverride
use ActionDispatch::Head
use ActionDispatch::BestStandardsSupport
run MyApp::Application.routes

The thing is that the second component, Rack::Lock is, as far as I know, a mutex wrapping the whole frigging rails stack (!).

Does this mean that there’s no concurrency in rails, no matter what platform you’re using? (I’m using JRuby).

I know I can delete the lock with:

config.middleware.delete(Rack::Lock)

But sadly that breaks everything. Does that mean my app is not threadsafe?

Answer 1

You should see the following entry in config/environments/production.rb

  # Enable threaded mode
  # config.threadsafe!

Uncomment in a JRuby or other thread-friendly environment to deploy in threadsafe mode.