一、问题描述

Redis Cluster集群，当master宕机，主从切换，客户端报错 timed out

二、原因

SpringBoot2.X版本开始Redis默认的连接池都是采用的Lettuce。当节点发生改变后，Letture默认是不会刷新节点拓扑的。

三、解决方案

3.1 方案一：把lettuce换成jedis

只需要在pom.xml里调整一下依赖的引用

      <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-data-redis</artifactId>
           <version>2.1.5.RELEASE</version>
               <!-- 不用lettuce ,用jedis -->
               <exclusions>
                   <exclusion>
                       <groupId>io.lettuce</groupId>
                       <artifactId>lettuce-core</artifactId>
                   </exclusion>
               </exclusions>
       </dependency>


       <dependency>
           <groupId>redis.clients</groupId>
           <artifactId>jedis</artifactId>
           <version>3.1.0-m4</version>
       </dependency>

3.2 方案二：刷新节点拓扑视图

Redis节点异常，服务端的Redis集群拓扑被刷新了，Java程序没有获取到新的拓扑。

Lettuce官方文档中关于Redis Cluster的相关说明：Lettuce处理Moved和Ask永久重定向，由于命令重定向，你必须刷新节点拓扑视图。而自适应拓扑刷新（Adaptive updates）与定时拓扑刷新（Periodic updates）是默认关闭的，可以通过如下代码打开。

https://github.com/lettuce-io/lettuce-core/wiki/Redis-Cluster#user-content-refreshing-the-cluster-topology-view

Lettuce

修改代码如下

package com.montnets.common.redis;

import io.lettuce.core.ClientOptions;
import io.lettuce.core.cluster.ClusterClientOptions;
import io.lettuce.core.cluster.ClusterTopologyRefreshOptions;
import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.data.redis.RedisProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.connection.RedisClusterConfiguration;
import org.springframework.data.redis.connection.RedisNode;
import org.springframework.data.redis.connection.RedisPassword;
import org.springframework.data.redis.connection.lettuce.LettuceClientConfiguration;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
import org.springframework.data.redis.connection.lettuce.LettucePoolingClientConfiguration;
import org.springframework.stereotype.Component;

import java.time.Duration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

@Component
public class RedisPoolConfig {

    @Autowired
    private RedisProperties redisProperties;

    public GenericObjectPoolConfig<?> genericObjectPoolConfig(RedisProperties.Pool properties) {
        GenericObjectPoolConfig<?> config = new GenericObjectPoolConfig<>();
        config.setMaxTotal(properties.getMaxActive());
        config.setMaxIdle(properties.getMaxIdle());
        config.setMinIdle(properties.getMinIdle());
        if (properties.getTimeBetweenEvictionRuns() != null) {
            config.setTimeBetweenEvictionRunsMillis(properties.getTimeBetweenEvictionRuns().toMillis());
        }
        if (properties.getMaxWait() != null) {
            config.setMaxWaitMillis(properties.getMaxWait().toMillis());
        }
        return config;
    }

    @Bean(destroyMethod = "destroy")
    public LettuceConnectionFactory lettuceConnectionFactory() {

        //开启 自适应集群拓扑刷新和周期拓扑刷新
        ClusterTopologyRefreshOptions clusterTopologyRefreshOptions =  ClusterTopologyRefreshOptions.builder()
                // 开启全部自适应刷新
                .enableAllAdaptiveRefreshTriggers() // 开启自适应刷新,自适应刷新不开启,Redis集群变更时将会导致连接异常
                // 自适应刷新超时时间(默认30秒)
                .adaptiveRefreshTriggersTimeout(Duration.ofSeconds(30)) //默认关闭开启后时间为30秒
                // 开周期刷新
                .enablePeriodicRefresh(Duration.ofSeconds(20))  // 默认关闭开启后时间为60秒 ClusterTopologyRefreshOptions.DEFAULT_REFRESH_PERIOD 60  .enablePeriodicRefresh(Duration.ofSeconds(2)) = .enablePeriodicRefresh().refreshPeriod(Duration.ofSeconds(2))
                .build();

        // https://github.com/lettuce-io/lettuce-core/wiki/Client-Options
        ClientOptions clientOptions = ClusterClientOptions.builder()
                .topologyRefreshOptions(clusterTopologyRefreshOptions)
                .build();

        LettuceClientConfiguration clientConfig = LettucePoolingClientConfiguration.builder()
                .poolConfig(genericObjectPoolConfig(redisProperties.getJedis().getPool()))
                //.readFrom(ReadFrom.MASTER_PREFERRED)
                .clientOptions(clientOptions)
                .commandTimeout(redisProperties.getTimeout()) //默认RedisURI.DEFAULT_TIMEOUT 60
                .build();

        List<String> clusterNodes = redisProperties.getCluster().getNodes();
        Set<RedisNode> nodes = new HashSet<RedisNode>();
        clusterNodes.forEach(address -> nodes.add(new RedisNode(address.split(":")[0].trim(), Integer.valueOf(address.split(":")[1]))));

        RedisClusterConfiguration clusterConfiguration = new RedisClusterConfiguration();
        clusterConfiguration.setClusterNodes(nodes);
        clusterConfiguration.setPassword(RedisPassword.of(redisProperties.getPassword()));
        clusterConfiguration.setMaxRedirects(redisProperties.getCluster().getMaxRedirects());

        LettuceConnectionFactory lettuceConnectionFactory = new LettuceConnectionFactory(clusterConfiguration, clientConfig);
        // lettuceConnectionFactory.setShareNativeConnection(false); //是否允许多个线程操作共用同一个缓存连接，默认true，false时每个操作都将开辟新的连接
        // lettuceConnectionFactory.resetConnection(); // 重置底层共享连接, 在接下来的访问时初始化
        return lettuceConnectionFactory;
    }
}