Delayed Job - Rails 4

Question

I have installed delayed job (gem 'delayed_job_active_record'), but I do not understand a couple of things about its functionality.

First of all after installing delayed_job, I would expect all my delay() methods to work out of the box, and not having to manually start delayed_job.

Now in the README it says that

script/delayed_job can be used to manage a background process which will start working off jobs.

After a few lines it mentions,

If you want to just run all available jobs and exit you can use rake jobs:work

What is the difference between those 2 and which one should I use in my production sever?

If I use rake jobs:work should I start a new thread in a initializer?

Thread.new do
   system(rake jobs:work)
end

Is that a good practice?

Answer 1

Use script/delayed_job for production - your capistrano deployment would call the following after pushing new code

RAILS_ENV=production script/delayed_job stop
RAILS_ENV=production script/delayed_job start

NOTE

Rails 4: replace script/delayed_job with bin/delayed_job

Usually in development I will execute jobs 'in-process', but optionally specify an environment var to run when I want to simulate production

see https://github.com/collectiveidea/delayed_job#gory-details - config/initializers/delayed_job_config.rb

# execute job synch during tests and dev
# or pass arg for async in those environments
delayed_execution = if ENV['DELAY_JOBS']
  true
else
  !(Rails.env.test? or Rails.env.development?)
end

Delayed::Worker.delay_jobs = delayed_execution

then if you want to run in dev with the delay in separate process boot up both rails and the job process - NOTE that delayed job does NOT auto load changes, you have to restart it each time

$ DELAY_JOBS=true rails s 
$ DELAY_JOBS=true bundle exec rake jobs:work