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 { @Autowired private 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> { @Autowired private 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: 8080
tomcat:
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。
