From: Abraham Tio <tio.a@...>
Date: 2007-12-31T12:52:37+09:00
Subject: a loop in a thread... very greedy

need a class(we'll call it a 'simulator' since that's what i'm
attempting to write) to run a loop.
need that loop to stop when asked to, such as when the user that started
it clicks a button to stop it.

i write java that does this sort of thing all the time.
HOWEVER, when i try it in ruby, only bad things happen.

check this out:

***start r.rb***
class Simulator
  attr_accessor :running
  attr_accessor :sim_thread
  def start
    running = true;
    puts "starting simulator..."
    sim_thread= Thread.new(){
      puts "sim thread started"
      while(running)
        300000.times do |x|
          x+=1
        end
        puts 'did a buncha stuff a simulator might do'
        Thread.pass
      end
      puts "sim thread stopped"
    }
    sim_thread.join
    sim_thread
  end
  def stop
    puts "stopping simulator..."
    running = false
  end
end
Thread.abort_on_exception = true
simulator = Simulator.new
thread = simulator.start
puts "started simulator, now we stop it.."
simulator.stop
***end r.rb***

i get no exceptions in the thread.
the output:
starting simulator...
sim thread started
did a buncha stuff a simulator might do
did a buncha stuff a simulator might do
did a buncha stuff a simulator might do

this line never executes:

puts "started simulator, now we stop it.."

why does ruby not leave the thread lone to do its thing,
and do other things ?

instead, it seems to get stuck in the while loop, as if i didn't put it
in a separate thread.

any help much appreciated, thanks.
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