Session 一致性

个人备忘

Nginx –ip_hash

找到nginx 安装目录下的 nginx.conf文件

//修改如下配置include  gzip.conf;           upstream localhost {               #ip_hash          ip_hash;          server localhost:8080;          server localhost:9080;         }  

优点 ：（1）配置简单，对应用无侵入性，不需要修改代码。（2）只要hash属性是均匀的，多台web-server的负载是均衡的（3）便于服务器水平扩展（4）安全性较高

缺点：（1）服务器重启造成部分session 丢失。（2）水平扩展中也会造成部分session丢失（3）存在单点负载高的风险（4）某台服务器宕机了，会造成部分用户访问慢的问题。//说明 ： 因为他有心跳机制。

服务器的session 复制

tomcat的session复制是基于IP组播(multicast)来完成的, 详细的IP组播介绍可以参考这里.
简单的说就是需要进行集群的tomcat通过配置统一的组播IP和端口来确定一个集群组, 当一个node的session发生变更的时候, 它会向IP组播发送变更的数据, IP组播会将数据分发给所有组里的其他成员(node).

server.xml 配置如下(这里所有的tomcat都在不同的物理主机, 如果在同一台主机上需要改tomcat的tcpListenPort)

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"                   channelSendOptions="8">            <Manager className="org.apache.catalina.ha.session.DeltaManager"                     expireSessionsOnShutdown="false"                     notifyListenersOnReplication="true"/>            <Channel className="org.apache.catalina.tribes.group.GroupChannel">              <Membership className="org.apache.catalina.tribes.membership.McastService"                          address="228.0.0.4"                          port="45564"                          frequency="500"                          dropTime="3000"/>              <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"                        address="auto"                        port="4000"                        autoBind="100"                        selectorTimeout="5000"                        maxThreads="6"/>              <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">                <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>              </Sender>              <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>              <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/>            </Channel>            <Valve className="org.apache.catalina.ha.tcp.ReplicationValve"                   filter=""/>            <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>            <Deployer className="org.apache.catalina.ha.deploy.FarmWarDeployer"                      tempDir="/tmp/war-temp/"                      deployDir="/tmp/war-deploy/"                      watchDir="/tmp/war-listen/"                      watchEnabled="false"/>            <ClusterListener className="org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener"/>            <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>  </Cluster> 

//优点（1）对应用无侵入性，不需要修改代码（2）能适应各种负载均衡策略（3）服务器重启或者宕机不会造成session丢失（4）安全性较高//缺点（1）session同步会有一定的延迟（2）占用内网带宽资源（3）受限制于内存资源，水平扩展能力差（4）服务器数量较多就GG（5）序列化反序列化消耗cpu 性能

坑

Session 统一缓存

基于redis , 利用redis 的 key 的过期时间来保证session 的失效时间（当session 有操作，过期时间ttl 会加长）。个人推荐使用这种，因为 redis 的hash存储跟 servlet session 存储很类似。

//优点（1）能适应各种负载均衡策略（2）服务器重启或者宕机不会造成session丢失（3）安全性较高（4）扩展能力强（5）适合集群数量大时使用//缺点（1）对应用有入侵，需要增加相关配置。（2）增加一次网络开销，用户体验降低（3）序列化反序列化消耗cpu性能

配置如下 ：

1. 增加redis client 和 spring session 依赖
2. 修改web.xml, 增加filter ： springSessionRepom.xml,增加spring-session-data-redispositoryFilter ;
3. 修改spring配置文件，在容器中注入spring session 和redis 相关的bean ；

//相关依赖<!-- Spring 整合 Redis --><dependency><!--  session 跨域到 redis中 ，解决Nginx反向代理问题。  -->    <groupId>org.springframework.session</groupId>    <artifactId>spring-session</artifactId>    <version>1.3.0.RELEASE</version>      </dependency> <dependency>    <groupId>redis.clients</groupId>    <artifactId>jedis</artifactId>    <version>2.8.0</version></dependency>

//web.xml 配置<!-- 过滤器   session跨域 共享 --> <filter>     <filter-name>springSessionRepositoryFilter</filter-name>     <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> </filter> <filter-mapping>     <filter-name>springSessionRepositoryFilter</filter-name>     <url-pattern>/*</url-pattern> </filter-mapping>

// 注入bean
spring-redis.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"    xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="              http://www.springframework.org/schema/beans              http://www.springframework.org/schema/beans/spring-beans.xsd              http://www.springframework.org/schema/context              http://www.springframework.org/schema/context/spring-context.xsd">    <!-- redis 连接池   -->    <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">        <property name="maxTotal" value="${redis.pool.maxTotal}" />        <property name="maxIdle" value="${redis.pool.maxIdle}" />        <property name="minIdle" value="${redis.pool.minIdle}" />        <property name="testOnBorrow" value="${redis.pool.testOnBorrow}" />    </bean>    <bean id="jedisConnectionFactory"        class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">        <property name="hostName"   value="${redis.host}" />        <property name="port"       value="${redis.port}" />        <!-- <property name="password"   value="${redis.password}" /> -->        <property name="timeout"    value="${redis.timeout}" />          <property name="poolConfig" ref="jedisPoolConfig" />    </bean>    <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">        <property name="connectionFactory" ref="jedisConnectionFactory"></property>        <property name="keySerializer">            <bean                class="org.springframework.data.redis.serializer.StringRedisSerializer" />        </property>        <property name="valueSerializer">            <bean                class="org.springframework.data.redis.serializer.StringRedisSerializer" />        </property>    </bean>    <!-- Spring  session 用redis存储 -->    <bean id="redisHttpSessionConfiguration"            class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration">          <property name="maxInactiveIntervalInSeconds" value="${session.maxInactiveIntervalInSeconds}"  />     </bean> </beans>  

jedis.properties

redis.pool.maxTotal=100redis.pool.maxIdle=200redis.pool.minIdle=10redis.pool.maxActive=1024  redis.pool.maxWait=1000  redis.pool.testOnBorrow=true session.maxInactiveIntervalInSeconds=600redis.host=localhostredis.port=6379#redis.password=four2BeltTwoKingredis.timeout=100000

原理剖析

客户端发起请求–servlet 容器 – tomcat session 中获取session 对象。

应用 ：

最后一种重写代码 ：

重写httpServletRequest

重写getSession（）方法 。

package com.dongnao.jack.servlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class MyHttpServletRequest extends HttpServletRequestWrapper {    private HttpServletRequest req;    private HttpServletResponse resp;    public MyHttpServletRequest(HttpServletRequest request,            HttpServletResponse resp) {        super(request);        this.req = request;        this.resp = resp;    }    public HttpSession getSession() {        return new MyHttpSession(req, resp);    }}

子类MyHttpSession

重写 setAttribute() ， getAttribute() 两个方法，将数据存储到 缓存中（memcached,redis）, 然后去读取。

此方法跟spring-session 方法异曲同工。

package com.dongnao.jack.servlet;import java.util.Enumeration;import java.util.List;import java.util.UUID;import javax.servlet.ServletContext;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import javax.servlet.http.HttpSessionContext;import com.alibaba.fastjson.JSONObject;import com.dongnao.jack.redis.RedisApi;public class MyHttpSession implements HttpSession {    private HttpServletRequest req;    private HttpServletResponse resp;    private static String cacheKey = "sessionId";    private ThreadLocal<String> local = new ThreadLocal<String>();    public MyHttpSession(HttpServletRequest req, HttpServletResponse resp) {        this.req = req;        this.resp = resp;    }    public long getCreationTime() {        // TODO Auto-generated method stub        return 0;    }    public String getId() {        // TODO Auto-generated method stub        return null;    }    public long getLastAccessedTime() {        // TODO Auto-generated method stub        return 0;    }    public ServletContext getServletContext() {        // TODO Auto-generated method stub        return null;    }    public void setMaxInactiveInterval(int interval) {        // TODO Auto-generated method stub    }    public int getMaxInactiveInterval() {        // TODO Auto-generated method stub        return 0;    }    public HttpSessionContext getSessionContext() {        // TODO Auto-generated method stub        return null;    }    public Object getAttribute(String name) {        //1、从我们的cookie拿到对应的sessionID        String sessionId = this.getSessionIdFromCookie();        if (sessionId == null) {            return null;        }        //2、从redis中拿出对应的数据        List<String> list = RedisApi.lrange(sessionId);        return getValueByKey(name, list);    }    private Object getValueByKey(String key, List<String> list) {        for (String each : list) {            JSONObject jo = JSONObject.parseObject(each);            if (jo.containsKey(key)) {                return jo.get(key);            }        }        return null;    }    public Object getValue(String name) {        // TODO Auto-generated method stub        return null;    }    public Enumeration<String> getAttributeNames() {        // TODO Auto-generated method stub        return null;    }    public String[] getValueNames() {        // TODO Auto-generated method stub        return null;    }    /*      * 我们在这个方法里面，必须要把我们的信息存储到我们的redis缓存中     */    public void setAttribute(String name, Object value) {        //1我们要把redis的key存储到哪里去？必须要满足每一次jack老师的请求必须要从redis中找到唯一对应的那个session信息        //我们必须要把我们的key存储到我们的cookie        String sessionId = getSessionIdFromCookie();        if (sessionId == null) {            sessionId = local.get();            if (sessionId == null) {                sessionId = "dnjack#" + UUID.randomUUID();                local.set(sessionId);            }        }        //2、把我们的信息存储到redis服务中        JSONObject jo = new JSONObject();        jo.put(name, value);        RedisApi.lpush(sessionId, jo.toJSONString());        //3、把sessoinId存储到我们的cookie        writeCooke(sessionId);    }    private void writeCooke(String sessinId) {        Cookie cookie = new Cookie(cacheKey, sessinId);        cookie.setPath("/");        resp.addCookie(cookie);    }    private String getSessionIdFromCookie() {        Cookie[] cookies = req.getCookies();        if (cookies != null) {            for (Cookie cookie : cookies) {                if (cacheKey.equals(cookie.getName())) {                    return cookie.getValue();                }            }        }        return null;    }    public void putValue(String name, Object value) {        // TODO Auto-generated method stub    }    public void removeAttribute(String name) {        // TODO Auto-generated method stub    }    public void removeValue(String name) {        // TODO Auto-generated method stub    }    public void invalidate() {        // TODO Auto-generated method stub    }    public boolean isNew() {        // TODO Auto-generated method stub        return false;    }}

拦截器

加入我们重写后的MyHttpServletRequest 。

package com.dongnao.jack.servlet;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//@WebFilter(urlPatterns = "/*")public class MyFilter implements Filter {    public void init(FilterConfig filterConfig) throws ServletException {        // TODO Auto-generated method stub    }    //实例化MyHttpServletRequest    public void doFilter(ServletRequest request, ServletResponse response,            FilterChain chain) throws IOException, ServletException {        chain.doFilter(new MyHttpServletRequest((HttpServletRequest)request,                (HttpServletResponse)response), response);    }    public void destroy() {    }}

redis连接池

package com.dongnao.jack.redis;import java.io.IOException;import java.io.InputStream;import java.util.List;import java.util.Map;import java.util.Properties;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPool;import redis.clients.jedis.JedisPoolConfig;public class RedisApi {    private static JedisPool pool;    private static Properties prop = null;    static {        InputStream in = RedisApi.class.getClassLoader()                .getResourceAsStream("com/agui/redis/redis.properties");        prop = new Properties();        try {            prop.load(in);        }        catch (IOException e) {            e.printStackTrace();        }        JedisPoolConfig config = new JedisPoolConfig();        config.setMaxTotal(Integer.valueOf(prop.getProperty("MAX_TOTAL")));        config.setMaxIdle(Integer.valueOf(prop.getProperty("MAX_IDLE")));        config.setMaxWaitMillis(Integer.valueOf(prop.getProperty("MAX_WAIT_MILLIS")));        config.setTestOnBorrow(Boolean.valueOf(prop.getProperty("TEST_ON_BORROW")));        config.setTestOnReturn(Boolean.valueOf(prop.getProperty("TEST_ON_RETURN")));        config.setTestWhileIdle(Boolean.valueOf(prop.getProperty("TEST_WHILE_IDLE")));        pool = new JedisPool(config, prop.getProperty("REDIS_IP"),                Integer.valueOf(prop.getProperty("REDIS_PORT")), 100000);    }    /**     * 获取连接池     */    public static JedisPool getPool() {        if (pool == null) {            JedisPoolConfig config = new JedisPoolConfig();            config.setMaxTotal(Integer.valueOf(prop.getProperty("MAX_TOTAL")));            config.setMaxIdle(Integer.valueOf(prop.getProperty("MAX_IDLE")));            config.setMaxWaitMillis(Integer.valueOf(prop.getProperty("MAX_WAIT_MILLIS")));            config.setTestOnBorrow(Boolean.valueOf(prop.getProperty("TEST_ON_BORROW")));            config.setTestOnReturn(Boolean.valueOf(prop.getProperty("TEST_ON_RETURN")));            config.setTestWhileIdle(Boolean.valueOf(prop.getProperty("TEST_WHILE_IDLE")));            pool = new JedisPool(config, prop.getProperty("REDIS_IP"),                    Integer.valueOf(prop.getProperty("REDIS_PORT")));        }        return pool;    }    public static void returnResource(JedisPool pool, Jedis redis) {        if (redis != null) {            pool.returnResource(redis);        }    }    public static Long hdel(String key, String key1) {        Jedis jedis = null;        try {            jedis = pool.getResource();            return jedis.hdel(key, key1);        }        catch (Exception e) {        }        finally {            returnResource(pool, jedis);        }        return null;    }    /**      * get     *       * @param key      * @return      */    public static String get(String key) {        Jedis jedis = null;        String value = null;        try {            jedis = pool.getResource();            value = jedis.get(key);        }        catch (Exception e) {        }        finally {            returnResource(pool, jedis);        }        return value;    }    /**     * set     */    public static String set(String key, String value) {        Jedis jedis = null;        try {            jedis = pool.getResource();            return jedis.set(key, value);        }        catch (Exception e) {            return "0";        }        finally {            returnResource(pool, jedis);        }    }    public static String set(String key, String value, int expire) {        Jedis jedis = null;        try {            jedis = pool.getResource();            jedis.expire(key, expire);            return jedis.set(key, value);        }        catch (Exception e) {            return "0";        }        finally {            returnResource(pool, jedis);        }    }    public static Long del(String key) {        Jedis jedis = null;        try {            jedis = pool.getResource();            return jedis.del(key);        }        catch (Exception e) {            return null;        }        finally {            returnResource(pool, jedis);        }    }    public static Long lpush(String key, String... strings) {        Jedis jedis = null;        try {            jedis = pool.getResource();            return jedis.lpush(key, strings);        }        catch (Exception e) {            return 0L;        }        finally {            returnResource(pool, jedis);        }    }    public static List<String> lrange(String key) {        Jedis jedis = null;        String value = null;        try {            jedis = pool.getResource();            return jedis.lrange(key, 0, -1);        }        catch (Exception e) {            return null;        }        finally {            returnResource(pool, jedis);        }    }    public static String hmset(String key, Map map) {        Jedis jedis = null;        try {            jedis = pool.getResource();            return jedis.hmset(key, map);        }        catch (Exception e) {            return "0";        }        finally {            returnResource(pool, jedis);        }    }    public static List<String> hmget(String key, String... strings) {        Jedis jedis = null;        String value = null;        try {            jedis = pool.getResource();            return jedis.hmget(key, strings);        }        catch (Exception e) {        }        finally {            returnResource(pool, jedis);        }        return null;    }}

redis.property文件

MAX_TOTAL = 10000#控制一个pool最多有多少个状态为idle(空闲的)的jedis实例MAX_IDLE = 10#表示当borrow(引入)一个jedis实例时，最大的等待时间，如果超过等待时间，则直接抛出JedisConnectionException；MAX_WAIT = 100000#在borrow一个jedis实例时，是否提前进行validate操作；如果为true，则得到的jedis实例均是可用的TEST_ON_BORROW = true#在进行returnObject对返回的connection进行validateObject校验TEST_ON_RETURN = true#表示当borrow(引入)一个jedis实例时，最大的等待时间，如果超过等待时间，则直接抛出JedisConnectionException；  MAX_WAIT_MILLIS = 100000#从Redis host redis服务器IP 101.200.129.112REDIS_IP = 39.108.193.58#从Redis redis服务器portREDIS_PORT = 6379#定时对线程池中空闲的链接进行validateObject校验TEST_WHILE_IDLE =true#定时对线程池中空闲的链接进行validateObject校验1#定时对线程池中空闲的链接进行validateObject校验2#定时对线程池中空闲的链接进行validateObject校验3#定时对线程池中空闲的链接进行validateObject校验4