Start or ensure that Delayed Job runs when an application/server restarts

Question

We have to use delayed_job (or some other background-job processor) to run jobs in the background, but we\'re not allowed to change the boot scripts/boot-levels on the serve

Answer 1

Some more cleanup ideas: The "begin" is not needed. You should rescue "no such process" in order not to fire new processes when something else goes wrong. Rescue "no such file or directory" as well to simplify the condition.

DELAYED_JOB_PID_PATH = "#{Rails.root}/tmp/pids/delayed_job.pid"

def start_delayed_job
  Thread.new do 
    `ruby script/delayed_job start`
  end
end

def daemon_is_running?
  pid = File.read(DELAYED_JOB_PID_PATH).strip
  Process.kill(0, pid.to_i)
  true
rescue Errno::ENOENT, Errno::ESRCH   # file or process not found
  false
end

start_delayed_job unless daemon_is_running?

Keep in mind that this code won't work if you start more than one worker. And check out the "-m" argument of script/delayed_job which spawns a monitor process along with the daemon(s).