instance method flush

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 727
      def flush(minimum_idle = @idle_timeout)
        return if minimum_idle.nil?

        removed_connections = synchronize do
          return if self.discarded?

          idle_connections = @connections.select do |conn|
            !conn.in_use? && conn.seconds_idle >= minimum_idle
          end.sort_by { |conn| -conn.seconds_idle } # sort longest idle first

          # Don't go below our configured pool minimum unless we're flushing
          # everything
          idles_to_retain =
            if minimum_idle > 0
              @min_connections - (@connections.size - idle_connections.size)
            else
              0
            end

          if idles_to_retain > 0
            idle_connections.pop idles_to_retain
          end

          idle_connections.each do |conn|
            conn.lease

            @available.delete conn
            @connections.delete conn
          end
        end

        removed_connections.each do |conn|
          conn.disconnect!
        end
      end