Ribbon load balancing strategy

The material of this article comes from

Introduction to Ribbon

Spring Cloud Ribbon is a client-side load balancing tool based on HTTP and TCP, which is implemented based on Netflix Ribbon. Through the encapsulation of Spring Cloud, we can easily automatically convert service-oriented REST template requests into client-side load balancing service calls.

Ribbon principle

1. The service consumer initiates a request
2. LoadBalancerInterceptor intercepts the request
3. RibbonLoadBanlancerClient obtains the id of the service provider according to the uri in the request
4. Pulls the service list from the eureka server through the DynamicServerListLoadBalancer according to the id 5. Passes
Ribbon load balancing rules choose a service

Ribbon load balancing strategy

Ribbon's load balancing rules are defined through the IRule interface, and each implementation class is a rule

Built-in load balancing rule class	describe
RoundRobinRule	Simply poll the service list to select a server. It is Ribbon's default load balancing rule.
AvailabilityFilteringRule	Ignore the following two servers
WeightedResponseTimeRule	Assign a weight value to each server. The longer the server response time, the lower the weight of this server. This weight value will affect the server selection.
ZoneAvoidanceRule	Server selection is based on the servers available in the region. Use Zone to classify servers, and then poll multiple services within the Zone.
BestAvailableRule	Ignore those short-circuiting servers and choose servers with lower concurrency counts.
RandomRule	An available server is randomly selected.
RetryRule	Selection logic for retry mechanism

Modify Ribbon Load Balancing Policy

the first way

Define the implementation class of IRule in the configuration class

@Bean
    public IRule randomRule(){
    
    
        return new RandomRule();
    }

the second way

Configure in the configuration file application.yml file

userservice:
  ribbon:
    #负载均衡规则
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

starvation loading

Ribbon uses lazy loading by default, that is, the LoadBalanceClient will be created when it is accessed for the first time, and the request time will be very long. The starvation load will be created when the project starts, reducing the time-consuming of the first access

userservice:
  ribbon:
    eager-load:
      #开启饥饿加载
      enabled: true
      #指定对多个服务饥饿加载
      clients: 
        - userservice 
        - yyyyservice
        - xxxxservice