Delayed extensions

Sidekiq includes a similar feature to DelayedJob which allows you to make ActiveRecord method calls and ActionMailer deliveries asynchronous.

ActionMailer

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.

UserMailer.delay.welcome_email(@user.id)
UserMailer.delay_for(5.days).find_more_friends_email(@user.id)
UserMailer.delay_until(5.days.from_now).find_more_friends_email(@user.id)

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

ActiveRecord

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

User.delay.delete_old_users('some', 'params')
@user.delay.update_orders(1, 2, 3)
User.delay_for(2.weeks).whatever
User.delay_until(2.weeks.from_now).whatever

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 This stores object state in Redis and which can get out of date, causing stale data problems.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

Advanced Options

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

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

Troubleshooting

The delay extensions use YAML to dump the entire object instance to Redis. The psych engine is the only supported YAML engine; this is the default engine in Ruby 1.9. If you see a YAML dump/load stack trace, make sure syck is not listed.

Objects which contain Procs can be dumped but cannot be loaded by Psych. This can happen with ActiveRecord models that use the Paperclip gem. IMO this is a Ruby bug.

o = Object.new
o.instance_variable_set :@foo, Proc.new { 'hello world' }
yml = YAML.dump(o) # works!
YAML.load(yml) # BOOM