gistfile1.txt

      def checkin(conn)
        synchronize do
          conn.run_callbacks :checkin do
            conn.expire
            @queue.signal
          end

          release conn
        end
      end

      private

      def release(conn)
        thread_id = nil

        if @reserved_connections[current_connection_id] == conn
          thread_id = current_connection_id
        else
          thread_id = @reserved_connections.keys.find { |k| # BOOM GOES HERE
            @reserved_connections[k] == conn
          }
        end

        @reserved_connections.delete thread_id if thread_id
      end