bulk_make_new_connections

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 581
      def bulk_make_new_connections(num_new_conns_needed)
        num_new_conns_needed.times do
          # try_to_checkout_new_connection will not exceed pool's @size limit
          if new_conn = try_to_checkout_new_connection
            # make the new_conn available to the starving threads stuck @available Queue
            checkin(new_conn)
          end
        end
      end