My previous deep dive into the Rails 4.0 Queueing system was motivated by a patch to Rails I was working on while at RailsCamp New England this past weekend. I’m happy to say that Rails 4.0 now has an optional asynchronous ActionMailer.
The API for pushing your emails to the background is very simple. If you
want to make this change application wide simply set it in your
application.rb (or in any of the environment files)
config.action_mailer.async = true
Or if you want to only make specific mailers asynchrounous
class WelcomeMailer < ActionMailer::Base self.async = true end
That’s it! Any messages that are being delivered will be sent as a background job. In fact, the rendering is happening on the background as well.
You will need to take care that the arguments you are passing your mailers can be properly marshalled. Instead of:
You should do:
Then in your mailer:
class WelcomeMailer < ActionMailer::Base def welcome(id) @user = User.find(id) ... end end
Switching it up
The default queueing system is
Rails.queue, but you can override this to use any queueing system you
want by overriding
class WelcomeMailer < ActionMailer::Base def queue MyQueue.new end end
Your custom queue should expect the jobs to respond to
#run, same as
Much of the original code was cribbed (with permission) from Nick Plante’s resque_mailer gem.