title: delayed_job queue not being processed on Heroku
body: <p>I'm running a Rails 3 app with delayed_job. The issue I've come across is that though the app is correctly adding jobs to the queue, they are never being processed.</p>
  
  <p><strong>My Class</strong></p>
  
  <pre><code>class User &lt; ActiveRecord::Base
    after_create :send_welcome_email
  
    private
  
      def send_welcome_email
        UserMailer.delay.welcome_email(self)
      end
  end
  </code></pre>
  
  <p>Inspecting things through the Rails console I can see that there are jobs in the queue. I can also see that there have been 0 attempts to perform the jobs. Spinning up a Heroku worker doesn't cause the jobs to be processed.</p>
  
  <p>Any ideas?</p>
  
  <p>Thanks!</p>
  
  <p><strong>Edit: Trying to clear the jobs queue as suggested below I ran <code>rake jobs:clear</code> and received the following error</strong></p>
  
  <pre><code>rake aborted!
  uninitialized constant Rake::DSL
  /app/.bundle/gems/ruby/1.9.1/gems/rake-0.9.0/lib/rake/tasklib.rb:8:in `&lt;class:TaskLib&gt;'
  /app/.bundle/gems/ruby/1.9.1/gems/rake-0.9.0/lib/rake/tasklib.rb:6:in `&lt;module:Rake&gt;'
  /app/.bundle/gems/ruby/1.9.1/gems/rake-0.9.0/lib/rake/tasklib.rb:3:in `&lt;top (required)&gt;'
  /app/.bundle/gems/ruby/1.9.1/gems/rake-0.9.0/lib/rake/rdoctask.rb:20:in `&lt;top (required)&gt;'
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/tasks/documentation.rake:1:in `&lt;top (requ
  ired)&gt;'
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:15:in `block in &lt;top (required)&gt;
  '
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:6:in `each'
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:6:in `&lt;top (required)&gt;'
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:214:in `initialize_tasks'
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:139:in `load_tasks'
  /app/.bundle/gems/ruby/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:77:in `method_missing'
  /app/Rakefile:7:in `&lt;top (required)&gt;'
  /usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2373:in `load'
  /usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2373:in `raw_load_rakefile'
  /usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2007:in `block in load_rakefile'
  /usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
  /usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2006:in `load_rakefile'
  /usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:1991:in `run'
  /usr/ruby1.9.2/bin/rake:31:in `&lt;main&gt;'
  </code></pre>