互联网高并发之Hystrix实现服务隔离和降级

当大多数人在使用Tomcat时，多个HTTP服务会共享一个线程池，假设其中一个HTTP服务访问的数据库响应非常慢，这将造成服务响应时间延迟增加，大多数线程阻塞等待数据响应返回，导致整个Tomcat线程池都被该服务占用，甚至拖垮整个Tomcat。因此，如果我们能把不同HTTP服务隔离到不同的线程池，则某个HTTP服务的线程池满了也不会对其他服务造成灾难性故障。这就需要线程隔离或者信号量隔离来实现了。

使用线程隔离或信号隔离的目的是为不同的服务分配一定的资源，当自己的资源用完，直接返回失败而不是占用别人的资源。

Hystrix实现服务隔离两种方案

Hystrix的资源隔离策略有两种，分别为：线程池和信号量。

线程池方式

1、使用线程池隔离可以完全隔离第三方应用，请求线程可以快速放回。 2、请求线程可以继续接受新的请求，如果出现问题线程池隔离是独立的不会影响其他应用。
3、当失败的应用再次变得可用时，线程池将清理并可立即恢复，而不需要一个长时间的恢复。
4、独立的线程池提高了并发性

缺点：
线程池隔离的主要缺点是它们增加计算开销（CPU）。每个命令的执行涉及到排队、调度和上下文切换都是在一个单独的线程上运行的。

每个服务接口都有自己独立的线程池，管理运行当前自己的接口。但是cpu开销比较大

在同一个线程池中，素有请求全部到一个服务进行访问，这时候会导致其他服服务没有线程接收请求访问，所以就会产生服务雪崩效应

Member：

pom:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.itmayeidu</groupId><artifactId>member</artifactId><version>0.0.1-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.0.RELEASE</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient --><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId></dependency><!-- https://mvnrepository.com/artifact/com.alibaba/fastjson --><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.47</version></dependency></dependencies>
</project>

　　controller

package com.toov5.controller;import java.util.HashMap;
import java.util.Map;import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/member")
public class MemberController {@RequestMapping("/memberIndex")public Object memberIndex() throws InterruptedException {Map<String, Object> hashMap = new HashMap<String, Object>();hashMap.put("code", 200);hashMap.put("msg", "memberIndex");Thread.sleep(1500);return hashMap;}}

启动类

package com.toov5.controller;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class AppMember {public static void main(String[] args) {SpringApplication.run(AppMember.class, args);}}

yml：

server:port: 8081

Order

pom

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.itmayeidu</groupId><artifactId>order</artifactId><version>0.0.1-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.0.RELEASE</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient --><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId></dependency><!-- https://mvnrepository.com/artifact/com.alibaba/fastjson --><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.47</version></dependency><dependency><groupId>com.netflix.hystrix</groupId><artifactId>hystrix-metrics-event-stream</artifactId><version>1.5.12</version></dependency><dependency><groupId>com.netflix.hystrix</groupId><artifactId>hystrix-javanica</artifactId><version>1.5.12</version></dependency></dependencies></project>

　controller

package com.toov5.controller;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import com.alibaba.fastjson.JSONObject;
import com.toov5.hystrix.OrderHystrixCommand;
import com.toov5.hystrix.OrderHystrixCommand2;
import com.toov5.service.MemberService;@RestController
@RequestMapping("/order")
public class OrderController {@Autowiredprivate MemberService memberService;@RequestMapping("/orderIndex")public Object orderIndex() throws InterruptedException {JSONObject member = memberService.getMember(); //返回值与OrderHystrixCommand中的泛型对应System.out.println("当前线程名称:" + Thread.currentThread().getName() + ",订单服务调用会员服务:member:" + member);return member;}// 已经理解@RequestMapping("/orderIndexHystrix")public Object orderIndexHystrix() throws InterruptedException {return new OrderHystrixCommand(memberService).execute();}@RequestMapping("/findOrderIndex")public Object findIndex() {System.out.println("当前线程:" + Thread.currentThread().getName() + ",findOrderIndex");return "findOrderIndex";}
}

service

package com.toov5.service;import org.springframework.stereotype.Service;import com.alibaba.fastjson.JSONObject;
import com.toov5.utils.HttpClientUtils;@Service
public class MemberService {public JSONObject getMember() {JSONObject result = HttpClientUtils.httpGet("http://127.0.0.1:8081/member/memberIndex");return result;}}

utils

package com.toov5.utils;import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import java.io.IOException;/*** HttpClient4.3工具类* * @author hang.luo*/
public class HttpClientUtils {private static Logger logger = LoggerFactory.getLogger(HttpClientUtils.class); // 日志记录private static RequestConfig requestConfig = null;static {// 设置请求和传输超时时间requestConfig = RequestConfig.custom().setSocketTimeout(2000).setConnectTimeout(2000).build();}/*** post请求传输json参数* * @param url*            url地址* @param json*            参数* @return*/public static JSONObject httpPost(String url, JSONObject jsonParam) {// post请求返回结果CloseableHttpClient httpClient = HttpClients.createDefault();JSONObject jsonResult = null;HttpPost httpPost = new HttpPost(url);// 设置请求和传输超时时间
        httpPost.setConfig(requestConfig);try {if (null != jsonParam) {// 解决中文乱码问题StringEntity entity = new StringEntity(jsonParam.toString(), "utf-8");entity.setContentEncoding("UTF-8");entity.setContentType("application/json");httpPost.setEntity(entity);}CloseableHttpResponse result = httpClient.execute(httpPost);// 请求发送成功，并得到响应if (result.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {String str = "";try {// 读取服务器返回过来的json字符串数据str = EntityUtils.toString(result.getEntity(), "utf-8");// 把json字符串转换成json对象jsonResult = JSONObject.parseObject(str);} catch (Exception e) {logger.error("post请求提交失败:" + url, e);}}} catch (IOException e) {logger.error("post请求提交失败:" + url, e);} finally {httpPost.releaseConnection();}return jsonResult;}/*** post请求传输String参数 例如：name=Jack&sex=1&type=2* Content-type:application/x-www-form-urlencoded* * @param url*            url地址* @param strParam*            参数* @return*/public static JSONObject httpPost(String url, String strParam) {// post请求返回结果CloseableHttpClient httpClient = HttpClients.createDefault();JSONObject jsonResult = null;HttpPost httpPost = new HttpPost(url);httpPost.setConfig(requestConfig);try {if (null != strParam) {// 解决中文乱码问题StringEntity entity = new StringEntity(strParam, "utf-8");entity.setContentEncoding("UTF-8");entity.setContentType("application/x-www-form-urlencoded");httpPost.setEntity(entity);}CloseableHttpResponse result = httpClient.execute(httpPost);// 请求发送成功，并得到响应if (result.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {String str = "";try {// 读取服务器返回过来的json字符串数据str = EntityUtils.toString(result.getEntity(), "utf-8");// 把json字符串转换成json对象jsonResult = JSONObject.parseObject(str);} catch (Exception e) {logger.error("post请求提交失败:" + url, e);}}} catch (IOException e) {logger.error("post请求提交失败:" + url, e);} finally {httpPost.releaseConnection();}return jsonResult;}/*** 发送get请求* * @param url*            路径* @return*/public static JSONObject httpGet(String url) {// get请求返回结果JSONObject jsonResult = null;CloseableHttpClient client = HttpClients.createDefault();// 发送get请求HttpGet request = new HttpGet(url);request.setConfig(requestConfig);try {CloseableHttpResponse response = client.execute(request);// 请求发送成功，并得到响应if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {// 读取服务器返回过来的json字符串数据HttpEntity entity = response.getEntity();String strResult = EntityUtils.toString(entity, "utf-8");// 把json字符串转换成json对象jsonResult = JSONObject.parseObject(strResult);} else {logger.error("get请求提交失败:" + url);}} catch (IOException e) {logger.error("get请求提交失败:" + url, e);} finally {request.releaseConnection();}return jsonResult;}}

Hystrix：

package com.toov5.hystrix;import org.springframework.beans.factory.annotation.Autowired;import com.alibaba.fastjson.JSONObject;
import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixCommandProperties;
import com.netflix.hystrix.HystrixThreadPoolKey;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import com.toov5.service.MemberService;@SuppressWarnings("rawtypes")
public class OrderHystrixCommand extends HystrixCommand<JSONObject> {@Autowiredprivate MemberService memberService;/*** @param group*/public OrderHystrixCommand(MemberService memberService) {super(setter());  //隔离this.memberService = memberService;}//表示服务执行的代码protected JSONObject run() throws Exception {JSONObject member = memberService.getMember();System.out.println("当前线程名称:" + Thread.currentThread().getName() + ",订单服务调用会员服务:member:" + member);return member;}private static Setter setter() {// 服务分组  相同的会员是一组HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("members");// 服务标识HystrixCommandKey commandKey = HystrixCommandKey.Factory.asKey("member");// 线程池名称HystrixThreadPoolKey threadPoolKey = HystrixThreadPoolKey.Factory.asKey("member-pool");// 线程池配置 线程池大小为10,线程存活时间15秒 队列等待的阈值为100,超过100执行拒绝策略HystrixThreadPoolProperties.Setter threadPoolProperties = HystrixThreadPoolProperties.Setter().withCoreSize(10).withKeepAliveTimeMinutes(15).withQueueSizeRejectionThreshold(100);// 命令属性配置Hystrix 开启超时HystrixCommandProperties.Setter commandProperties = HystrixCommandProperties.Setter()// 采用线程池方式实现服务隔离
                .withExecutionIsolationStrategy(HystrixCommandProperties.ExecutionIsolationStrategy.THREAD)// 禁止.withExecutionTimeoutEnabled(true);return HystrixCommand.Setter.withGroupKey(groupKey).andCommandKey(commandKey).andThreadPoolKey(threadPoolKey).andThreadPoolPropertiesDefaults(threadPoolProperties).andCommandPropertiesDefaults(commandProperties);}@Override    //降级protected JSONObject getFallback() {// 如果Hystrix发生熔断，当前服务不可用,直接执行Fallback方法System.out.println("系统错误！");JSONObject jsonObject = new JSONObject();jsonObject.put("code", 500);jsonObject.put("msg", "系统错误！");return jsonObject;}
}

启动类：

package com.toov5;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class AppOrder {public static void main(String[] args) {SpringApplication.run(AppOrder.class, args);}}

yml：

server:port: 8080tomcat:max-threads: 20

效果：

可以看到（开启超时），不同的线程池，服务隔离，服务降级。

转载于:https://www.cnblogs.com/toov5/p/9986857.html