Ruby 1.9.1 sticks

require 'thread'

$queue = Queue.new

workers = Array.new(100).map do
  Thread.new do
    block = $queue.pop
    block.call()
  end
end

100.times do
  $queue.push(lambda {
                pid = Process.fork do
                  puts :hoge
                end
                Process.waitpid(pid)
              })
end

workers.map(&:join)