限流降级

使用 Sentinel 保护您的应用,防止应用因个别服务的突发流量过载而出现稳定性问题。

Sentinel 是什么

随着微服务的流行,服务和服务之间的稳定性变得越来越重要。Sentinel 是面向分布式、多语言异构化服务架构的流量治理组件,主要以流量为切入点,从流量路由、流量控制、流量整形、熔断降级、系统自适应过载保护、热点流量防护等多个维度来帮助开发者保障微服务的稳定性。

一、示例架构说明

接口定义:

public interface FooService {

    String sayHello(String name);
}

接口实现:

@DubboService(timeout = 3000)
public class FooServiceImpl implements FooService {

    @Override
    public String sayHello(String name) {
        return String.format("Hello, %s at %s", name, LocalDateTime.now());
    }
}

限流配置:

FlowRule flowRule = new FlowRule(FooService.class.getName())
        .setCount(10)
        .setGrade(RuleConstant.FLOW_GRADE_QPS);
FlowRuleManager.loadRules(Collections.singletonList(flowRule));

二、快速启动示例

Step 1: 下载源码

git clone -b master https://github.com/apache/dubbo-samples.git
cd ./dubbo-samples-sentinel/

Step 2: 构建用例

执行 maven 命令,打包 demo 工程

mvn clean package

Step 3: 启动 Provider

java -classpath ./target/dubbo-samples-sentinel-1.0-SNAPSHOT.jar org.apache.samples.sentinel.FooProviderBootstrap

Step 4: 启动 OrderService

java -classpath ./target/dubbo-samples-sentinel-1.0-SNAPSHOT.jar org.apache.samples.sentinel.FooConsumerBootstrap

可以看到控制台输出中,Blocked 代表已经开始拦截。

Success: Hello, dubbo at 2022-08-08T15:42:40.809
Success: Hello, dubbo at 2022-08-08T15:42:40.812
Success: Hello, dubbo at 2022-08-08T15:42:40.815
Success: Hello, dubbo at 2022-08-08T15:42:40.818
Success: Hello, dubbo at 2022-08-08T15:42:40.821
Success: Hello, dubbo at 2022-08-08T15:42:40.823
Success: Hello, dubbo at 2022-08-08T15:42:40.826
Success: Hello, dubbo at 2022-08-08T15:42:40.828
Success: Hello, dubbo at 2022-08-08T15:42:40.830
Success: Hello, dubbo at 2022-08-08T15:42:40.834
Blocked
Blocked
Blocked
Blocked
Blocked

关于 Sentinel 的更多使用方式可以参考:Sentinel 为 Dubbo 服务保驾护航Sentinel 官网


最后修改 August 11, 2022: Enhance docs (#1365) (a90ac41f0)