ReferenceGlossary
Power of two choices
A load balancing method: pick two servers at random and send the request to the less loaded one. Mitzenmacher showed that two random choices spread load exponentially better than one, and the balancer needs no exact, shared view of every server's load. NGINX offers it as random two least_conn.
Performance
In Quorum#
With Load balancing algorithms researched, a Load Balancer can use Two choices. It keeps no global state, so the Load Balancer itself handles 1.5 times the traffic, but 10% of the traffic is split evenly whatever each server's load. Least conn splits fully by current capacity, without the capacity bonus.