Thread scheduling question

This code sends a message around a ring of queues. When each queue
pops, it prints out its message.

The code seems to work, but it seems to hang on the io, which I don’t
understand. I would expect the messages to print very quickly. The
messages only print inside of irb when I depress the carriage return
repeatedly.

Thank you!

Jeff

=================================
require ‘thread’

class Ring
attr_writer :size, :mbox, :agents
attr_reader :size, :mbox, :agents

def initialize (size)
@size = size
@mbox = []
@agents = []
(1…size).each do
@mbox << Queue.new
end

(0..size-1).each do |index|
  @agents << Thread.new(index) do |i|
    loop do
      msg = @mbox[i].pop
      case msg
          when "start"
            @mbox[(i+1)%size] << 1 if i == 0

          when "halt"
              break

          else
              print("#{i}: #{msg}: #{Thread.current} #{Time.now}\n")
          STDOUT.flush
          (@mbox[(i+1)%size] << msg + 1) if i!=0
          Thread.pass
      end
    end
  end
end

end

def rpc(i, msg)
@mbox[i] << msg
end

def start ()
rpc(0,“start”)
end

def halt ()
@mbox.each { |m| m << “halt” }
@agents.each {|thr| thr.join }
end

end

R = Ring.new(10)
R.start

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