instance method with_new_connections_blocked

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 666
      def with_new_connections_blocked
        synchronize do
          @threads_blocking_new_connections += 1
        end

        yield
      ensure
        num_new_conns_required = 0

        synchronize do
          @threads_blocking_new_connections -= 1

          if @threads_blocking_new_connections.zero?
            @available.clear

            num_new_conns_required = num_waiting_in_queue

            @connections.each do |conn|
              next if conn.in_use?

              @available.add conn
              num_new_conns_required -= 1
            end
          end
        end

        bulk_make_new_connections(num_new_conns_required) if num_new_conns_required > 0
      end