capistrano snippet for restarting delayed_job plugin

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

namespace :delayed_job do
  desc "Stop the delayed_job process"
  task :stop, :roles => :app do
    run "cd #{current_path}; script/delayed_job -e #{rails_env} stop"
  end
 
  desc "Start the delayed_job process"
  task :start, :roles => :app do
    run "cd #{current_path}; script/delayed_job -e #{rails_env} start -n 3"
  end
 
  desc "Restart the delayed_job process"
  task :restart, :roles => :app do
    stop
    wait_for_process_to_end('delayed_job')
    start
  end
end

def wait_for_process_to_end(process_name)
  run "COUNT=1; until [ $COUNT -eq 0 ]; do COUNT=`ps -ef | grep -v 'ps -ef' | grep -v 'grep' | grep -i '#{process_name}'|wc -l` ; echo 'waiting for #{process_name} to end' ; sleep 2 ; done"
end

2.0.3 of delayed_job (possibly earlier, not sure), dropped support for the '-e' switch, so now you would want:

run "cd #{current_path}; #{rails_env} script/delayed_job stop"

See:
http://github.com/collectiveidea/delayed_job/issues/issue/7