>_<.

#!/usr/local/bin/ruby
require 'thread'

queue = Queue.new

producer = Thread.new do
    5.times do |i|
        sleep rand(i) # simulate expense
        queue << i
        puts "#{i} produced"
    end
end

consumer = Thread.new do
    5.times do |i|
        value = queue.pop
        sleep rand(i/2) # simulate expense
        puts "consumed #{value}"
    end
end

producer.join
consumer.join

0 produced
1 produced
consumed 0
consumed 1
2 produced
3 produced
consumed 2
4 produced
consumed 3
consumed 4