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。