Question

I’m trying to use delayed_job gem https://github.com/collectiveidea/delayed_job in Rails 3.2 to send a mail in the background.

I installed the gem

 gem 'delayed_job_active_record'

I generated the table and ran the migrations, as instructed

$ rails generate delayed_job:active_record
$ rake db:migrate

Noting that there are special instructions for mailers in Rails 3

     # without delayed_job
Notifier.signup(@user).deliver

# with delayed_job
Notifier.delay.signup(@user)

I did

 def send_welcome_email

    #UserMailer.welcome_email(self).deliver  <-- original code that worked

   UserMailer.delay.welcome_email(self)        

  end

but the mail isn’t sending. It was working before I tried to use delayed_job…

Can someone clarify for a novice…?

Answer 1

Did you start at least 1 delayed_job worker?

rake jobs:work

Actually, when you call delayon an object, you are only queuing a job. Which means that a new entry will be created inside the DelayedJob table that contains all the metadata associated with your job.

So you still need something that will browse all your DelayedJobentries and run them one by one and that thing is the rake task (worker) shown above.

For production, it depends where you are deploying your application. On Heroku you only have to specify how many workers (Worker dynos) you need and they will start automatically.