background jobs

gistfile1.txt

Here's what I do:

This is Rails 2

pid = fork do
  %x{RAILS_ENV=#{Rails.env} #{RAILS_ROOT + "/script/runner"} '#{script}'}
  exit!
end
Process.detach pid

For Rails 3 you need to do this:

pid = fork do
  %x{RAILS_ENV=#{Rails.env} rails runner '#{script}'}
  exit!
end
Process.detach pid


So we fork, then run a system script that runs up rails in a new process.  The forked 
process will wait for the rails runner process to finish, so we just detach from that 
and forget it.

Your rails environment is there in the runner environment, so the way I do things is to 
write the Job I need to do to the database first, then make my script read it.

So I have a class called Job, and I write some job details to the jobs table.

When the process is started it reads those details and runs whatever image processing you 
need then writes a done timestamp to the table. Which is what this command does:

Job.find_by_id(#{id}).run


So the whole action looks something like this:

job = Job.create(:filename=>"image_file_whatever", :parameters=>"something")
script = "Job.find_by_id(#{job.id}).run"
pid = fork do
  %x{RAILS_ENV=#{Rails.env} rails runner '#{script}'}
  exit!
end
Process.detach pid