SpringCloud Alibaba-03 Sentinel服务熔断与限流

与CircuitBreaker功能类似



后台默认8719端口
前台默认8080端口

在jar包所在目录下打开CMD，执行 java -jar sentinel-dashboard-1.8.6.jar 命令即可

网址http://localhost:8080 账号密码都是sentinel

1.Sentinel微服务8401纳入Sentinel监控
1.1 建Module，改pom

    <dependencies>
        <!--SpringCloud alibaba sentinel -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <!--nacos-discovery-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!-- 引入自己定义的api通用包 -->
        <dependency>
            <groupId>com.dc.cloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!--SpringBoot通用依赖模块-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--hutool-->
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
            <scope>provided</scope>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

1.2 改yml

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848         #Nacos服务注册中心地址
    sentinel:
      transport:
        dashboard: localhost:8080 #配置Sentinel dashboard控制台服务地址
        port: 8719 #默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口

1.3 主启动

@EnableDiscoveryClient
@SpringBootApplication
public class Main8401
{
    public static void main(String[] args)
    {
        SpringApplication.run(Main8401.class,args);
    }
}

1.4 业务类

@RestController
public class FlowLimitController
{

    @GetMapping("/testA")
    public String testA()
    {
        return "------testA";
    }

    @GetMapping("/testB")
    public String testB()
    {
        return "------testB";
    }
}

2.Sentinel流控规则

2.1 流控模式

2.1.1 直接
1秒钟支持2次访问

超过两次

2.1.2 关联
B超过1秒钟1次，限流A

jmeter模拟高并发访问testB (在jmeter的bin目录下双击jmeter.bat即可启动)

4秒后testA才能访问

2.1.3 链路
新建FlowLimitService类

@Service
public class FlowLimitService
{
    @SentinelResource(value = "common")
    public void common()
    {
        System.out.println("------FlowLimitService come in");
    }
}

controller地哦啊用service

    /**流控-链路演示demo
     * C和D两个请求都访问flowLimitService.common()方法，阈值到达后对C限流，对D不管
     */
    @Resource
    private FlowLimitService flowLimitService;

    @GetMapping("/testC")
    public String testC()
    {
        flowLimitService.common();
        return "------testC";
    }
    @GetMapping("/testD")
    public String testD()
    {
        flowLimitService.common();
        return "------testD";
    }

修改yml

    sentinel:
      transport:
        dashboard: localhost:8080 #配置Sentinel dashboard控制台服务地址
        port: 8719 #默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口
    web-context-unify: false # controller层的方法对service层调用不认为是同一个根链路

testC进行限流（不超过1秒1次），testD不受影响

2.2 流控效果

2.2.1 快速失败

2.2.2 Warm Up 预热
刚开始每秒钟（10/3约等于3）3次请求，5秒后每秒钟10次请求

2.2.3 排队等待

1秒允许一个通过，超过10秒还未响应的进行超时处理，放弃

2.3 并发线程数