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Ok, so this is probably evil, however.. here's the question! I want to run a pretty lightweight app on a shared environment (site5). Ideally I would like to use delayed_job for the ease of queueing the mails (~200+ every so often). However, being a shared environment they don't want background processes running all the time (fair enough).

So, my plan, such as it is, is to queue the mails using delayed job, and then every hour or something, spin up a cron job, send a few emails (10 or something small) and then kill the process. And repeat.

Q) Is there a rake jobs:works:1 equivalent task it'd be easy to setup? - pointer would be handy.

I'm quite open to "this is a terrible idea, don't even go there" being the answer.. in which case I might look at another queuing strategy... (or heroku hire-fire perhaps..)

patrickdavey
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2 Answers2

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You can get delayed job to process only a certain number of jobs by doing:

Delayed::Worker.new.work_off(10)

You could fire a script to do that from cron or use "rails runner":

rails runner -e production 'Delayed::Worker.new.work_off(10)'

I guess the main issue on whether it is a good idea or not is working out what small value is actually high enough to make sure you process all your jobs in a reasonable time-frame. Also, you've got the overhead of firing up the rails environment every time you want to process, or even check whether you should process, any jobs. That might cause problems in a shared environment if they are particularly strict on spikes of memory or CPU usage.

Shadwell
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  • it's going to be rare enough (like only a couple of times a year ~200 mails a pop) that I might just schedule a cron task to run the above only for those periods... that hopefully will keep everyone happy ;) Many thanks. – patrickdavey Jul 26 '12 at 19:48
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Why not skip the 'workers' (which are just daemons which look for work else sleep) and have your cron fire a custom rake task of 10.times { MailerJob.first.perform }

You'd just need to require you're app in the line before that so its loaded ofc.

TomDunning
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  • noob question here.. but how is MailerJob getting defined? I'm assuming the aim is to look at the delayed job queue and do the first job. – patrickdavey Jul 26 '12 at 19:57
  • Ah yes. I've skipped a step. The 'accept' rightly went to the other answer. Normally with asynchronous stuff it's conventional to add a 'jobs' folder inside 'app' and definite any jobs you'd like your workers to perform in there. Often these are as short as: User.find(id).some_method – TomDunning Jul 26 '12 at 20:25
  • Anyway; it needs to access and update the delayed jobs queue, so shadwell is exactly right. – TomDunning Jul 26 '12 at 20:26