def clean!
      HotTub.logger.info "[HotTub] Cleaning pool #{@name}!" if HotTub.logger
      @mutex.synchronize do
        begin
          @_pool.each do |clnt|
            clean_client(clnt)
          end
        ensure
          @cond.signal
        end
      end
      nil
    end
def clean!
      HotTub.logger.info "[HotTub] Cleaning pool #{@name}!" if HotTub.logger
      @mutex.synchronize do
        begin
          @_pool.each do |clnt|
            clean_client(clnt)
          end
        ensure
          @cond.signal
        end
      end
      nil
    end
Clean all clients currently checked into the pool.
 Its possible clients may be returned to the pool after cleaning