def flush
      mon = Splib::Monitor.new
      @threads.size.times{ queue{ mon.wait } }
      @queue.wait_empty
      sleep(0.01)
      mon.broadcast
    end
def flush
      mon = Splib::Monitor.new
      @threads.size.times{ queue{ mon.wait } }
      @queue.wait_empty
      sleep(0.01)
      mon.broadcast
    end
Flush the thread pool. Mainly used for forcibly resizing
 the pool if existing threads have a long thread life waiting
 for input.