Delayed extensions

Mike Perham edited this page Oct 15, 2015 · 40 revisions

Delayed extensions provide a very easy and simple way to make method calls asynchronous. By default, all class methods and ActionMailer deliveries can be performed asynchronously.


Use delay to deliver your emails asynchronously. Use delay_for(interval) or delay_until(time) to deliver the email at some point in the future.


It is recommended to avoid passing an object instance to mailer methods. Instead, pass an object id and then re-instantiate the object in the mailer method, per Best Practices.

You can also easily extend the devise gem to send emails using sidekiq.


Use delay, delay_for(interval), or delay_until(time) to asynchronously execute arbitrary methods on your ActiveRecord classes.

User.delay.delete_old_users('some', 'params')

I strongly recommend avoiding delaying methods on instances. This stores object state in Redis which can get out of date, causing stale data problems.

Class Methods

Any class method can be delayed via the same methods as above:

MyClass.delay.some_method(1, 'bob', true)

Just remember to keep the method arguments simple, don't pass complex Ruby objects.

Advanced Options

You can tune the options used with a .delay call by passing in options:

MyClass.delay(:retry => false).some_method(1, 2, 3)
MyClass.delay(:queue => 'low').some_method(1, 2, 3)
MyClass.delay_for(10.minutes, :retry => false).some_method(1, 2, 3)

Disabling Extensions

The delay extensions can conflict with DelayedJob if you want to run both in the same process. You can disable them in a Rails application by calling Sidekiq.remove_delay! in an initializer. This will prevent the delay extension modules from ever being loaded. If you would like to include the delay extensions prefixed with sidekiq_ (i.e., sidekiq_delay, sidekiq_delay_for and sidekiq_delay_until), call Sidekiq.hook_rails! first in your initializer:

# config/initializers/sidekiq.rb
# Sidekiq.hook_rails! # uncomment if you want the delay extensions, but prefixed with `sidekiq_`

If you are using Sidekiq outside of a Rails application, the class method extensions are always loaded.

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