I've just switched to using Unicorn on Heroku. I'm also going to switch to resque from delayed_job and use the setup described at http://bugsplat.info/2011-11-27-concurrency-on-heroku-cedar.html
What I don't understand from this is how config/unicorn.rb:
worker_processes 3
timeout 30
@resque_pid = nil
before_fork do |server, worker|
@resque_pid ||= spawn("bundle exec rake " + \
"resque:work QUEUES=scrape,geocode,distance,mailer")
end
translates into:
"This will actually result in six processes in each web dyno: 1 unicorn master, 3 unicorn web workers, 1 resque worker, 1 resque child worker when it actually is processing a job"
How many workers will actually process background jobs? 1 or 2?
Lets say I wanted to increase the number of resque workers - what would I change?
I think if you run that block, you have your unicorn master already running, plus 3 web workers that you specify at the top of the file, and then the block below launches one Resque worker if it's not already started.
I'm guessing that Resque launches a child worker by itself when it actually performs work.
It would appear that if you wanted another Resque worker, you could just do
In my experience with Resque, it's as simple as launching another process as specified above. The only uncertainty I have is with Heroku and how it chooses to deal with giving you more workers.