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spring feign 总结启用

项目中增加依赖

org.springframework.cloud spring-cloud-starter-openfeign io.github.openfeign feign-httpclient 10.12

激活配置启动类添加载 @EnableFeignClients 如下：

@SpringBootApplication @ComponentScans({@ComponentScan(value = "com.lydemo", excludeFilters = {@ComponentScan.Filter(IgnoreMark.class)})}) @ServletComponentScan("com.lydemo.helloworld.filter") @EnableFeignClients public class BootApplication {

基础配置包括超时，httpclient，日志配置

# feign配置 feign.httpclient.max-connections=200 feign.httpclient.max-connections-per-route=50 feign.httpclient.connection-timeout=1500 feign.client.config.default.connect-timeout=1500 feign.client.config.default.read-timeout=5000 feign.client.config.default.loggerLevel=BASIC 重试机制

总结：

feign 的调用逻辑入口： feign.SynchronousMethodHandler#invokefeign 自身默认不启用重试： Retryer.NEVER_RETRY （一般建议不用开启）

配置解析：通过 org.springframework.cloud.openfeign.FeignClient#configuration 字段注释发现默认配置在 org.springframework.cloud.openfeign.FeignClientsConfiguration

// org.springframework.cloud.openfeign.FeignClientsConfiguration#feignRetryer @Bean @ConditionalOnMissingBean public Retryer feignRetryer() { return Retryer.NEVER_RETRY; }

参考：

https://cloud.tencent.com/developer/article/1083249 （老的用ribbon）https://codeleading.com/article/46553623072/ （feign 和 ribbon 重试机制对比）启用 LoadBalancer 重试

说明

当不启用（LoadBalancer 重试）时候 client 是FeignBlockingLoadBalancerClient ，当启用重试时候 RetryableFeignBlockingLoadBalancerClient ，重试策略是 InterceptorRetryPolicy代码执行逻辑在： org.springframework.cloud.openfeign.loadbalancer.RetryableFeignBlockingLoadBalancerClient#execute （spring boot 配置在org.springframework.cloud.openfeign.loadbalancer.DefaultFeignLoadBalancerConfiguration#feignRetryClient）重试机制默认也未开启

启用配置增加如下依赖：

org.springframework.retry spring-retry

添加如下配置

# loadbalancer 配置 # loadbalancer 配置 (retry.enabled 也会控制 RetryableFeignBlockingLoadBalancerClient 的生成) spring.cloud.loadbalancer.retry.enabled=true spring.cloud.loadbalancer.retry.max-retries-on-same-service-instance=0 spring.cloud.loadbalancer.retry.max-retries-on-next-service-instance=1

重试测试

logback 添加如下配置

启动两个被调用实例（我启动了helo2 demo 微服务），然后快速停止其中一个，快速点击调用方实例，出现如下日志：

重试日志如下

remote.feign.Helo2Client - [log,72] - [Helo2Client#queryUserByName] ---> GET http://HELO2/helo2/queryUserByName?name=lala&sign=2e3817293fc275dbee74bd71ce6eb056 HTTP/1.1 2021-07-25 01:54:29.508 [http-nio-46092-exec-7] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,120] - Service instance retrieved from LoadBalancedRetryContext: was null. Reattempting service instance selection 2021-07-25 01:54:29.510 [http-nio-46092-exec-7] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,128] - Selected service instance: [EurekaServiceInstance@6b1e9f0 instance = InstanceInfo [instanceId = helo2:192.168.3.6:42379, appName = HELO2, hostName = 192.168.3.6, status = UP, ipAddr = 192.168.3.6, port = 42379, securePort = 443, dataCenterInfo = com.netflix.appinfo.MyDataCenterInfo@2fff1f76] 2021-07-25 01:54:29.510 [http-nio-46092-exec-7] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,146] - Using service instance from LoadBalancedRetryContext: [EurekaServiceInstance@6b1e9f0 instance = InstanceInfo [instanceId = helo2:192.168.3.6:42379, appName = HELO2, hostName = 192.168.3.6, status = UP, ipAddr = 192.168.3.6, port = 42379, securePort = 443, dataCenterInfo = com.netflix.appinfo.MyDataCenterInfo@2fff1f76] 2021-07-25 01:54:29.514 [http-nio-46092-exec-7] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,120] - Service instance retrieved from LoadBalancedRetryContext: was null. Reattempting service instance selection 2021-07-25 01:54:29.523 [http-nio-46092-exec-7] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,128] - Selected service instance: [EurekaServiceInstance@6996f084 instance = InstanceInfo [instanceId = helo2:192.168.3.6:8080, appName = HELO2, hostName = 192.168.3.6, status = UP, ipAddr = 192.168.3.6, port = 8080, securePort = 443, dataCenterInfo = com.netflix.appinfo.MyDataCenterInfo@781923c7] 2021-07-25 01:54:29.523 [http-nio-46092-exec-7] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,146] - Using service instance from LoadBalancedRetryContext: [EurekaServiceInstance@6996f084 instance = InstanceInfo [instanceId = helo2:192.168.3.6:8080, appName = HELO2, hostName = 192.168.3.6, status = UP, ipAddr = 192.168.3.6, port = 8080, securePort = 443, dataCenterInfo = com.netflix.appinfo.MyDataCenterInfo@781923c7] 2021-07-25 01:54:29.533 [http-nio-46092-exec-7] DEBUG com.lydemo.helloworld.remote.feign.Helo2Client - [log,72] - [Helo2Client#queryUserByName] GET http://HELO2/helo2/queryUserByName?name=lala&sign=2e3817293fc275dbee74bd71ce6eb056 HTTP/1.1 2021-07-25 02:10:55.381 [http-nio-46092-exec-10] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,120] - Service instance retrieved from LoadBalancedRetryContext: was null. Reattempting service instance selection 2021-07-25 02:10:55.382 [http-nio-46092-exec-10] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,128] - Selected service instance: [EurekaServiceInstance@4a2d6add instance = InstanceInfo [instanceId = helo2:192.168.3.6:8080, appName = HELO2, hostName = 192.168.3.6, status = UP, ipAddr = 192.168.3.6, port = 8080, securePort = 443, dataCenterInfo = com.netflix.appinfo.MyDataCenterInfo@781923c7] 2021-07-25 02:10:55.382 [http-nio-46092-exec-10] DEBUG org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient - [lambda$execute$2,146] - Using service instance from LoadBalancedRetryContext: [EurekaServiceInstance@4a2d6add instance = InstanceInfo [instanceId = helo2:192.168.3.6:8080, appName = HELO2, hostName = 192.168.3.6, status = UP, ipAddr = 192.168.3.6, port = 8080, securePort = 443, dataCenterInfo = com.netflix.appinfo.MyDataCenterInfo@781923c7] 2021-07-25 02:10:55.387 [http-nio-46092-exec-10] DEBUG com.lydemo.helloworld.remote.feign.Helo2Client - [log,72] - [Helo2Client#queryUserByName]

配置

feign.circuitbreaker.enabled=true

因为添加了 resilience4j-spring-boot2 所以 resilience4j 可以如下配置：

# resilience4j circuitbreaker 配置 resilience4j.circuitbreaker: configs: default: slidingWindowType: COUNT_BASED slidingWindowSize: 100 minimumNumberOfCalls: 100 permittedNumberOfCallsInHalfOpenState: 10 automaticTransitionFromOpenToHalfOpenEnabled: true waitIntervalFunctionInOpenState: 60 failureRateThreshold: 50 eventConsumerBufferSize: 10 # recordExceptions: # - org.springframework.web.client.HttpServerErrorException # - java.io.IOException # ignoreExceptions: # - java.lang.IllegalStateException instances: testService: baseConfig: default slidingWindowSize: 10 minimumNumberOfCalls: 2 failureRateThreshold: 1 recordExceptions: - java.lang.Throwable

属性配置优先级高于Java Customizer configuration.

参考：

https://docs.spring.io/spring-cloud-circuitbreaker/docs/current/reference/html/#usage-documentation 。

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