require "thread" 
puts "ProAndCon" 

queue = Queue.new    #用隊列Queue實現線程同步 

producer = Thread.new do 
    10.times do |i| 
        sleep rand(i) # 讓線程睡眠一段時間 
        queue << i 
        puts "#{i} produced" 
    end 
end 

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

consumer.join  #等待consumer線程的輸出完成再關閉此進程