Ruby bounded thread worker pool

def run_pool(items, workers: 4)
  raise ArgumentError, 'workers must be positive' unless workers.positive?
  jobs = Queue.new
  results = Queue.new
  items.each_with_index { |item, index| jobs << [item, index] }
  workers.times { jobs << nil }
  threads = workers.times.map do
    Thread.new do
      while (job = jobs.pop)
        item, index = job
        begin
          results << [index, :ok, yield(item)]
        rescue StandardError => error
          results << [index, :error, error]
        end
      end
    end
  end
  threads.each(&:join)
  Array.new(items.size) { results.pop }.sort_by(&:first).map { |_, status, value| [status, value] }
end