Common Load-Balancing Algorithms

Static Algorithms

1. Round robin

   • The client requests are sent to different service instances in sequential order. The services are usually required to be stateless.

2. Sticky round-robin

   • This is an improvement of the round-robin algorithm. If Alice’s first request goes to service A, the following requests go to service A as well.

3. Weighted round-robin

   • The admin can specify the weight for each service. The ones with a higher weight handle more requests than others.

4. Hash

   • This algorithm applies a hash function on the incoming requests’ IP or URL. The requests are routed to relevant instances based on the hash function result.

Dynamic Algorithms

1. Least connections

   • A new request is sent to the service instance with the least concurrent connections.

2. Least response time

   • A new request is sent to the service instance with the fastest response time.