Comparison of top 3 Ruby background job systems on Ruby Toolbox

delayed_job.rb

# DelayedJob

@user.delay.activate!(@device) # Delay any object
Notifier.delay.signup(@user) # Delay ActionMailer

#DelayedJob supports a number of ways to make methods async
def send_mailer
  # Some other code
end
handle_asynchronously :send_mailer, :priority => 20

def in_the_future
  # Some other code
end
# 5.minutes.from_now will be evaluated when in_the_future is called
handle_asynchronously :in_the_future, :run_at => Proc.new { 5.minutes.from_now }

class NewsletterJob < Struct.new(:text, :emails)
  def perform
    emails.each { |e| NewsletterMailer.deliver_text_to_email(text, e) }
  end
end

# DJ's version of a worker class. No modules required. DJ stores the entire
# object in the database as YAML when it is enqueued.

Delayed::Job.enqueue NewsletterJob.new('lorem ipsum...', Customers.find(:all).collect(&:email))

resque.rb

# Resque 2

# As far as I can tell, enqueueing class or instance methods a la Sidekiq/DJ:
# @user.delay.update_orders(1, 2, 3)
# is not supported by Resque 2.0, though you could probably code it up yourself.

class ImageConversionJob
  def work
    # convert some kind of image here
  end
end

resque = Resque.new
resque << ImageConversionJob.new

# Resque 2 worker classes do not require inclusion of a module

sidekiq.rb

# Sidekiq

User.delay.do_some_stuff(current_user.id, 20) # Delay any class method
@user.delay.update_orders(1, 2, 3) # Delay any instance method
UserMailer.delay.welcome_email(@user.id)  # Delay ActionMailer
object.delay(:queue => 'tracking').method # Supports named queues

# Sidekiq supports but does not encourage delaying methods on instances

class HardWorker
  include Sidekiq::Worker

  def perform(name, count)
    puts 'Doing hard work'
  end
end

HardWorker.perform_async('bob', 5)

# Sidekiq's worker classes require you to include Sidekiq::Worker