available thread counts?

thread.rb

  #
  # Returns the number of threads waiting on the queue.
  #
  def num_waiting
    @num_waiting
  end
end

# when init EM env, there is a thread pool would be inited
# with default configutation. the `num_waiting` would be set as that value


#/usr/local/var/rbenv/versions/2.0.0-p598/lib/ruby/gems/2.0.0/gems/eventmachine-1.0.7/lib/em/pool.rb:106

    # A peek at the number of enqueued jobs waiting for resources #此处的` resources` 是指?
    def num_waiting
      @resources.num_waiting
    end

      unless EM.defers_finished?
        wait_count     = 0
        error_occurred = false
        binding.pry
        while EM.threadqueue.num_waiting == 0
          if (wait_count % MallConf.batch.em_thread.monitor.wait_count.display_frequency) == 0
            Rails.logger.info "All threads are busy. wait_count=#{wait_count}"
            if !error_occurred && (wait_count >= error_threshold)
              error_occurred = true
              Rails.logger.error "Threads are waiting long time. It may need to restart. wait_count=#{wait_count}"
            end
          end
          sleep 1
          wait_count += 1
        end

        # use error log level so that RAMEN send an alert mail
        Rails.logger.error "Threads start working. It was a false alarm. wait_count=#{wait_count}" if error_occurred
      end