From: David Masover <ninja@...>
Date: 2009-12-18T03:50:57+09:00
Subject: Re: Using threads to show progress

On Thursday 17 December 2009 11:51:10 am Piyush Ranjan wrote:
> So is using two threads is the best solution ?

It depends what you mean by "best".

The simplest solution, and hardest to get wrong, would be something like this:

  desc "Go through dictated exams and show IDs"
  task(:showSomeIDs => :environment) do
    interval = 0.1
    last_update = 0
    DictatedExam.all.each do |exam|
      if Time.now - last_update >= interval
        puts exam.id
        last_update = Time.now
      end
    end
  end

No threads involved at all. However, this has the problem that you could have 
several items take much faster than that interval to process, and then one 
takes a very long time -- in which case, the display would stop updating 
(which is good), but it would currently show the wrong id, not the id which is 
taking so long.

I don't know that this matters in this case, but if you did want a more 
accurate update, you'd probably want some sort of thread. But I'd hide that 
thread in a library, and I might not have it always poll.