如何在Heroku实例上运行循环进程（Rails 4）？

Question

I have a Heroku Rails 4 app where I want something to run continuously. It is processing data from Amazon SQS.

Right now, I use clock.rb to continuously add a delayed job to run a worker. The worker is set to run for 10m, then finishes. Since the clock.rb is running every 30 seconds, it should restart a new process pretty quickly.

My Procfile is:

myworker: QUEUE=myworker bundle exec rake jobs:work

I'm wondering if there is a way to change the Procfile perhaps, so that I could say "Every instance of myworker should run this process while it is alive. If it dies for whatever reason, restart it immediately and start processing again"

Is there a good way to do that with Rails 4 and Heroku?

There must be... I don't really know what this is called but surely there's a name for this.

Also, once I have it running, would there be a good way to say "close the process every 10m, and restart, just to clear your memory/restart fresh"?

Answer 1

You don't have to do it with Delayed Job or anything like that; you just have to create a custom Rake task.

For instance, at my work we have this line in our Procfile:

jobs_worker: bundle exec rake poll_jobs

We added a file_jobs.rake file in lib/tasks , which does this:

task poll_jobs: :environment do while true puts "polling jobs" FileJob.poll_status! sleep 10 end end

We put in the extra sleep 10 so that a replacement task doesn't spin up right away. But you can take that out. The moment your task completes, it will automatically be restarted again. Keep in mind that if you keep restarting too often, Heroku might get mad at you and not spin your task right up again.

You could just as easily put a timer in there, or a 'number of times you make it around the loop' - and exit when the timer expires, or the number of times you've been through the loop is greater than 'x'.

Does that make sense?