Rails Delayed Job

dyn — Thu, 25 Mar 2010 23:44:29 +0000

When building a web application, you always try to make it fast and responsive. Sometimes this task can be difficult because of some long running requests like: file uploads, sending email, updating sphinx indexes, running reports, etc.

Enter Delayed Job.

First, we must install the plugin and migrate the delayed_job table that handles the work:

1	script/plugin install git://github.com/collectiveidea/delayed_job.git

Then we create the table:

1 2	script/generate delayed_job rake db:migrate

Now we are ready to enqueue jobs. Let’s say we want to send an email with delayed_job:

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Emailer.deliver_contact(@comments) #old way

Emailer.send_later(:deliver_contact, @comments) #delayed_job way

Now you check your email and you can’t find anything. That’s because we need to run the delayed_job daemon.

1	script/delayed_job start

Now you can see how the daemon sends the email. Instead of the send_later method, you can “mark” a method to always run in background:

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class Photo
def generate_thumbnails
#generate all the thumbnails
end
handle_asynchronously :generate_thumbnails
end

@photo = Photo.new(params[:photo])
@photo.generate_thumbnails #this will run throught delayed_job

Now you need to run delayed_job in your production environment, with capistrano you should have something like:

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namespace :delayed_job do
desc "Start delayed_job process"
task :start, :roles => :app do
run "cd #{current_path}; RAILS_ENV=production script/delayed_job start"
end

desc "Stop delayed_job process"
task :stop, :roles => :app do
run "cd #{current_path}; RAILS_ENV=production script/delayed_job stop"
end

desc "Restart delayed_job process"
task :restart, :roles => :app do
run "cd #{current_path}; RAILS_ENV=production script/delayed_job restart"
end
end

after "deploy:start", "delayed_job:start"
after "deploy:stop", "delayed_job:stop"
after "deploy:restart", "delayed_job:restart"

If there’s an error when launching the daemon in production, that might be because you need the daemons gem. I had problems with the daemons 1.0.11 so I went for the ghazel-daemons and everything worked fine.

We highly recommend to use monit to monitor and restart the delayed_job process in case something goes wrong. You can check other options like custom jobs and configuration parameters in the docs.

Dyn Solutions » ruby on rails

Rails Delayed Job