I've got an app that could benefit from delayed_job and some background processing. The thing is, I don't really need/want delayed_job workers running all the time.
The app runs in a shared hosting environment and in multiple locations (for different users). Plus, the app doesn't get a large amount of usage.
Is there a way to start and stop processing jobs (either with the script or rake task) from my app only after certain actions/events?
You could call out to system:
system "cd #{Rails.root} && rake delayed_job:start RAILS_ENV=production"
You could just change delayed_job to check less often too. Instead of the 5 second default, set it to 15 minutes or something.
Yes, you can, but I'm not sure what the benefit will be. You say you don't want workers running all the time - what are your concerns? Memory usage? Database connections?
To keep the impact of delayed_job low on your system, I'd run only one worker, and configure it to sleep most of the time.
Delayed::Worker::sleep_delay = 60 * 5 # in your initializer.rb
A single worker will only wake up and check the db for new jobs every 5 minutes. Running this way keeps you from 'customizing' too much.
But if you really want to start a Delayed::Worker programatically, look in that class for work_off, and implement your own script/run_jobs_and_exit script. It should probably look much like script/delayed_job does - 3 lines.