require 'thread' class LocalBarrier def initialize(n) @wait = Queue.new @done = Queue.new @keeper = begin_keeper(n) end def sync @done.push(true) @wait.pop end def join @keeper.join end private def begin_keeper(n) Thread.start do n.times do @done.pop end n.times do @wait.push(true) end end end end n = 10 lb = LocalBarrier.new(n) (n - 1).times do |i| Thread.start do sleep((rand(n) + 1) / 10.0) print "#{i}: done\n" lb.sync print "#{i}: cont\n" end end lb.sync print "#{n-1}: cont\n" # lb.join # [ruby-dev:30653] print "exit.\n"