SpringCloud Alibaba Sentinel实现熔断与限流
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2021-04-06 19:21
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作者 | C紫枫
来源 | urlify.cn/f2MvAf
概述
简单来说是histrix的升级版，也是替换的新组件。
官网：https://github.com/alibaba/Sentinel
中文官网：https://github.com/alibaba/Sentinel/wiki/介绍
下载地址：https://github.com/alibaba/Sentinel/releases
安装Sentiel控制台
运行命令：java -jar sentinel-dashboard-1.7.0.jar
访问sentinel管理界面：http://localhost:8080（登录账号密码均为sentinel）
初始化演示功能cloudalibaba-sentinel-service8401
pom.xml
<!--SpringCloud ailibaba sentinel-datasource-nacos 后续做持久化用到-->
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-nacos</artifactId>
</dependency>
<!--SpringCloud ailibaba sentinel -->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
application.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地址
port: 8719
datasource:
ds1:
nacos:
server-addr: localhost:8848
dataId: cloudalibaba-sentinel-service
groupId: DEFAULT_GROUP
data-type: json
rule-type: flow
management:
endpoints:
web:
exposure:
include: '*'
feign:
sentinel:
enabled: true # 激活Sentinel对Feign的支持
启动类
package com.czf.springcloud;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class MainApp8401 {
public static void main(String[] args) {
SpringApplication.run(MainApp8401.class,args);
}
}
业务类FlowLimitController----限流
@SentinelResource的blockHandler的属性开启兜底方法
package com.czf.springcloud.controller;
import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.util.concurrent.TimeUnit;
/**
* @auther czf
* @create 2020-02-24 16:26
* 限流
*/
@RestController
@Slf4j
public class FlowLimitController
{
@GetMapping("/testA")
public String testA()
{
return "------testA";
}
@GetMapping("/testB")
public String testB()
{
log.info(Thread.currentThread().getName()+"\t"+"...testB");
return "------testB";
}
@GetMapping("/testD")
public String testD()
{
try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }
log.info("testD 测试RT");
/* log.info("testD 异常比例");
int age = 10/0;*/
return "------testD";
}
@GetMapping("/testE")
public String testE()
{
log.info("testE 测试异常数");
int age = 10/0;
return "------testE 测试异常数";
}
@GetMapping("/testHotKey")
@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")
public String testHotKey(@RequestParam(value = "p1",required = false) String p1,
@RequestParam(value = "p2",required = false) String p2)
{
int age = 10/0;
return "------testHotKey";
}
public String deal_testHotKey (String p1, String p2, BlockException exception) //兜底方法
{
return "------deal_testHotKey,o(╥﹏╥)o"; //sentinel系统默认的提示：Blocked by Sentinel (flow limiting)
}
}
自定义兜底类：CustomerBlockHandler
@GetMapping("/rateLimit/customerBlockHandler")
@SentinelResource(value = "customerBlockHandler",
blockHandlerClass = CustomerBlockHandler.class,
blockHandler = "handlerException2")
public CommonResult customerBlockHandler()
{
return new CommonResult(200,"按客戶自定义",new Payment(2020L,"serial003"));
}
}
package com.czf.springcloud.myhandler;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.czf.springcloud.entities.CommonResult;
/**
* @auther zzyy
* @create 2020-02-25 15:32
*/
public class CustomerBlockHandler
{
public static CommonResult handlerException(BlockException exception)
{
return new CommonResult(4444,"按客戶自定义,global handlerException----1");
}
public static CommonResult handlerException2(BlockException exception)
{
return new CommonResult(4444,"按客戶自定义,global handlerException----2");
}
}
流控规则
流控模式
1.直接(默认)
2.关联
当关联的资源达到阈值时，就限流自己。
3.链路
多个请求调用同一个微服务
流控效果
直接->快速失败(默认的流控处理)
直接失败，抛出异常。Blocked by Sentinel(flow limiting)
预热
说明：公式:阈值除以coldFactor(默认值为3)，经过预热时长后才会达到阈值
官网：
默认coldFactor为3，即请求QPS从threshold/3开始，经预热时长逐渐升至设定的QPS阈值
WarmUp配置：
效果：多次点击http://localhost:8401/testB，刚开始不行，后续慢慢OK
应用场景：如：秒杀系统在开启瞬间，会有很多流量上来，很可能把系统打死，预热方式就是为了保护系统，可慢慢的把流量放进来，慢慢的把阈值增长到设置的阈值。
排队等待
匀速排队，阈值必须设置为QPS
降级规则
熔断之后就会降级（给出错误消息提示）
官网：https://github.com/alibaba/Sentinel/wiki/熔断降级
基本介绍：QPS >=5且比例(秒级统计)超过阈值时，触发降级，时间窗口结束后，关闭降级
降级策略实战
1.RT
该请求需要1秒来完成，当RT（平均响应时间）为200毫秒,1秒远大于RT阈值。
@GetMapping("/testD")
public String testD()
{
try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }
log.info("testD 测试RT");
/* log.info("testD 异常比例");
int age = 10/0;*/
return "------testD";
}
2.异常比例
3.异常数
@GetMapping("/testE")
public String testE()
{
log.info("testE 测试异常数");
int age = 10/0;
return "------testE 测试异常数";
}
热点key限流
@GetMapping("/testHotKey")
@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")
public String testHotKey(@RequestParam(value = "p1",required = false) String p1,
@RequestParam(value = "p2",required = false) String p2)
{
//int age = 10/0;
return "------testHotKey";
}
public String deal_testHotKey (String p1, String p2, BlockException exception) //兜底方法
{
return "------deal_testHotKey,o(╥﹏╥)o"; //sentinel系统默认的提示：Blocked by Sentinel (flow limiting)
}
当第一个参数超过设置的阈值（1）就会降级报错
参数例外项
其他
手贱添加异常看看o(╥﹏╥)o
系统规则
官网介绍：https://github.com/alibaba/Sentinel/wiki/系统自适应限流
不合适,使用危险,一竹竿打死一船人
@SentinelResource
按资源名称限流+后续处理
@GetMapping("/byResource")
@SentinelResource(value = "byResource",blockHandler = "handleException")
public CommonResult byResource()
{
return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));
}
public CommonResult handleException(BlockException exception)
{
return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");
}
按照Url地址限流+后续处理
@GetMapping("/rateLimit/byUrl")
@SentinelResource(value = "byUrl")//url和这里的value都可以配置流控等，但必须唯一。value的值是资源名
public CommonResult byUrl() {
return new CommonResult(200, "按url限流测试OK", new Payment(2020L, "serial002"));
}
客户自定义限流处理逻辑
RateLimitController
@GetMapping("/rateLimit/customerBlockHandler")
@SentinelResource(value = "customerBlockHandler",
blockHandlerClass = CustomerBlockHandler.class,
blockHandler = "handlerException2")
public CommonResult customerBlockHandler() {
return new CommonResult(200, "按客戶自定义", new Payment(2020L, "serial003"));
}
CustomerBlockHandler
public class CustomerBlockHandler
{
public static CommonResult handlerException(BlockException exception)
{
return new CommonResult(4444,"按客戶自定义,global handlerException----1");
}
public static CommonResult handlerException2(BlockException exception)
{
return new CommonResult(4444,"按客戶自定义,global handlerException----2");
}
}
更多注解说明
官网：https://github.com/alibaba/Sentinel/wiki/注解支持
Sentinel主要有三个核心Api：
1.sphU定义资源
2.Tracer定义统计
3.ContextUtil定义了上下文
服务熔断功能
sentinel整合ribbon+openFeign+fallback
消费者84
提供者：9003、9004
cloudalibaba-consumer-nacos-order84(消费者)
pom.xml
<!--SpringCloud openfeign -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<!--SpringCloud ailibaba nacos -->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<!--SpringCloud ailibaba sentinel -->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
application.yml
server:
port: 84
spring:
application:
name: nacos-order-consumer
cloud:
nacos:
discovery:
server-addr: localhost:8848
sentinel:
transport:
#配置Sentinel dashboard地址
dashboard: localhost:8080
#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
port: 8719
#消费者将要去访问的微服务名称(注册成功进nacos的微服务提供者)
service-url:
nacos-user-service: http://nacos-payment-provider
# 激活Sentinel对Feign的支持
feign:
sentinel:
enabled: true
CircleBreakerController(ribbon/openFeign)
fallback管运行异常（例如空指针异常之类的）；blockHandler管配置违规（超过阈值之类的）
package com.czf.springcloud.controller;
import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.czf.springcloud.entities.CommonResult;
import com.czf.springcloud.entities.Payment;
import com.czf.springcloud.service.PaymentService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import javax.annotation.Resource;
/**
* @auther zzyy
* @create 2020-02-25 16:05
*/
@RestController
@Slf4j
public class CircleBreakerController
{
//----------------------------------ribbon----restTemplate
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
//@SentinelResource(value = "fallback") //没有配置
//@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback只负责运行异常，兜底,相当于服务降级
//@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler只负责sentinel控制台配置违规，违规兜底---主管配置违规
@SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler")
//exceptionsToIgnore = {IllegalArgumentException.class})
public CommonResult<Payment> fallback(@PathVariable Long id)
{
CommonResult<Payment> result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");
}
return result;
}
//本例是fallback
public CommonResult handlerFallback(@PathVariable Long id,Throwable e) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(444,"兜底异常handlerFallback,exception内容 "+e.getMessage(),payment);
}
//本例是blockHandler
public CommonResult blockHandler(@PathVariable Long id,BlockException blockException) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment);
}
//==================OpenFeign
@Resource
private PaymentService paymentService;
@GetMapping(value = "/consumer/paymentSQL/{id}")
public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id)
{
return paymentService.paymentSQL(id);
}
}
ribbon的配置
package com.czf.springcloud.config;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
/**
* ribbon的负载均衡
*/
@Configuration
public class ApplicationContextConfig
{
@Bean
@LoadBalanced
public RestTemplate getRestTemplate()
{
return new RestTemplate();
}
}
OpenFeign配置
package com.czf.springcloud.service;
import com.czf.springcloud.entities.CommonResult;
import com.czf.springcloud.entities.Payment;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
/**
*openFeign
*/
@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)
public interface PaymentService
{
@GetMapping(value = "/paymentSQL/{id}")
public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id);
}
运行异常配置
package com.czf.springcloud.service;
import com.czf.springcloud.entities.CommonResult;
import com.czf.springcloud.entities.Payment;
import org.springframework.stereotype.Component;
/**
* openFeign
*/
@Component
public class PaymentFallbackService implements PaymentService
{
@Override
public CommonResult<Payment> paymentSQL(Long id)
{
return new CommonResult<>(44444,"服务降级返回,---PaymentFallbackService",new Payment(id,"errorSerial"));
}
}
cloudalibaba-provider-payment9004
pom.xml
<!--SpringCloud ailibaba nacos -->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
application.yml
server:
port: 9004
spring:
application:
name: nacos-payment-provider
cloud:
nacos:
discovery:
server-addr: localhost:8848 #配置Nacos地址
management:
endpoints:
web:
exposure:
include: '*'
PaymentController
package springcloud.controller;
import com.czf.springcloud.entities.CommonResult;
import com.czf.springcloud.entities.Payment;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
/**
* @auther zzyy
* @create 2020-02-25 16:11
*/
@RestController
public class PaymentController
{
@Value("${server.port}")
private String serverPort;
public static HashMap<Long, Payment> hashMap = new HashMap<>();
static
{
hashMap.put(1L,new Payment(1L,"28a8c1e3bc2742d8848569891fb42181"));
hashMap.put(2L,new Payment(2L,"bba8c1e3bc2742d8848569891ac32182"));
hashMap.put(3L,new Payment(3L,"6ua8c1e3bc2742d8848569891xt92183"));
}
@GetMapping(value = "/paymentSQL/{id}")
public CommonResult<Payment> paymentSQL(@PathVariable("id") Long id)
{
Payment payment = hashMap.get(id);
CommonResult<Payment> result = new CommonResult(200,"from mysql,serverPort: "+serverPort,payment);
return result;
}
}
2者同时配置，达到配置阈值只会报blockHandler对应兜底方法的返回值信息
规则持久化
存在的问题
一旦我们重启应用,sentinel规则消失,生产环境需要将配置规则进行持久化。
怎么实现？
将限流规则持久进Nacos保存,只要刷新8401某个rest地址,sentinel控制台的流控规则就能看得到,只要Nacos里面的配置不删除,针对8401上的流控规则持续有效
cloudalibaba-sentinel-service8401
pom.xml
<!-- sentinel-datasource-nacos 后续持久化用 -->
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-nacos</artifactId>
</dependency>
application.yml
添加Nacos业务规则配置
[
{
"resource":"/rateLimit/byUrl",
"limitApp":"default",
"grade":1,
"count":1,
"strategy":0,
"controlBehavior":0,
"clusterMode":false
}
]
启动8401刷新sentinel发现业务规则变了
测试接口：http://localhost:8401/rateLimit/byUrl
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