Load balancer that is aware of the process

Hello, as to my knowlage load balancers like nginx (well nginx when uses like a load balancer) or Kemp only split requests in half or to a scalable fraction between all servers, is there any load balancers that can

A: send notifications to other processes to shut down if there is high traffic (configurable hooks)
or
B: send traffic to one server but if it's overwhelmed or hits a threshold send it to another