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更新时间：2024-11-26 GMT+08:00

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Lettuce客户端连接Redis（Java）

本章节介绍使用Lettuce客户端连接Redis实例的方法。更多的客户端的使用方法请参考Redis客户端。

在springboot类型的项目中，spring-data-redis中已提供了对jedis、lettuce的集成适配。另外，在springboot1.x中默认集成的是jedis，springboot2.x中改为了lettuce，因此在springboot2.x及更高版本中想集成使用lettuce，无需手动引入lettuce依赖包。

Springboot版本不得低于2.3.12.RELEASE，Lettuce版本不得低于6.3.0.RELEASE。

前提条件

已成功创建Redis实例，且状态为“运行中”。
查看并获取待连接Redis实例的IP地址/域名和端口。具体步骤请参见《分布式缓存服务用户指南》中“快速入门 > 查看实例信息”章节。

Pom配置

<!-- 引入spring-data-redis组件，默认已集成lettuce依赖SDK -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>io.lettuce</groupId>
    <artifactId>lettuce-core</artifactId>
    <version>${lettuce.version}</version>
</dependency>

基于application.properties配置

单机、主备、Proxy集群实例配置

#redis host
spring.redis.host=<host>
#redis 端口号
spring.redis.port=<port>
#redis 数据库下标
spring.redis.database=0
#redis 密码
spring.redis.password=<password>
#redis 读写超时
spring.redis.timeout=2000

Cluster集群实例配置

# redis cluster节点信息
spring.redis.cluster.nodes=<ip:port>,<ip:port>,<ip:port>
# redis cluster 最大重定向次数
spring.redis.cluster.max-redirects=3
# redis cluster 节点密码
spring.redis.password=<password>
# redis cluster 超时配置
spring.redis.timeout=2000
# 开启自适应拓扑刷新
spring.redis.lettuce.cluster.refresh.adaptive=true
# 开启每10S定时刷新拓扑结构
spring.redis.lettuce.cluster.refresh.period=10S

基于Bean方式配置

单机、主备、Proxy集群实例配置

import java.time.Duration;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
import org.springframework.data.redis.connection.lettuce.LettuceClientConfiguration;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;

import io.lettuce.core.ClientOptions;
import io.lettuce.core.SocketOptions;

/**
* Lettuce 非池化配置，与 application.properties 配置方式二选一
*/
@Configuration
public class RedisConfiguration {

    @Value("${redis.host}")
    private String redisHost;

    @Value("${redis.port:6379}")
    private Integer redisPort = 6379;

    @Value("${redis.database:0}")
    private Integer redisDatabase = 0;

    @Value("${redis.password:}")
    private String redisPassword;

    @Value("${redis.connect.timeout:2000}")
    private Integer redisConnectTimeout = 2000;

    @Value("${redis.read.timeout:2000}")
    private Integer redisReadTimeout = 2000;

    @Bean
    public RedisConnectionFactory redisConnectionFactory(LettuceClientConfiguration clientConfiguration) {

        RedisStandaloneConfiguration standaloneConfiguration = new RedisStandaloneConfiguration();
        standaloneConfiguration.setHostName(redisHost);
        standaloneConfiguration.setPort(redisPort);
        standaloneConfiguration.setDatabase(redisDatabase);
        standaloneConfiguration.setPassword(redisPassword);

        LettuceConnectionFactory connectionFactory = new LettuceConnectionFactory(standaloneConfiguration, clientConfiguration);
        connectionFactory.setDatabase(redisDatabase);
        return connectionFactory;
    }

    @Bean
    public LettuceClientConfiguration clientConfiguration() {

        SocketOptions socketOptions = SocketOptions.builder().connectTimeout(Duration.ofMillis(redisConnectTimeout)).build();

        ClientOptions clientOptions = ClientOptions.builder()
                .autoReconnect(true)
                .pingBeforeActivateConnection(true)
                .cancelCommandsOnReconnectFailure(false)
                .disconnectedBehavior(ClientOptions.DisconnectedBehavior.ACCEPT_COMMANDS)
                .socketOptions(socketOptions)
                .build();

        
        LettuceClientConfiguration clientConfiguration = LettuceClientConfiguration.builder()
                .commandTimeout(Duration.ofMillis(redisReadTimeout))
                .readFrom(ReadFrom.MASTER)
                .clientOptions(clientOptions)
                .build();

        return clientConfiguration;
    }
}

单机、主备、Proxy集群实例池化配置

引入池化组件

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-pool2</artifactId>
    <version>2.11.1</version>
</dependency>

代码配置

import java.time.Duration;

import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
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 io.lettuce.core.ClientOptions;
import io.lettuce.core.SocketOptions;

/**
* Lettuce 池化配置
*/
@Configuration
public class RedisPoolConfiguration {
    @Value("${redis.host}")
    private String redisHost;

    @Value("${redis.port:6379}")
    private Integer redisPort = 6379;

    @Value("${redis.database:0}")
    private Integer redisDatabase = 0;

    @Value("${redis.password:}")
    private String redisPassword;

    @Value("${redis.connect.timeout:2000}")
    private Integer redisConnectTimeout = 2000;

    @Value("${redis.read.timeout:2000}")
    private Integer redisReadTimeout = 2000;

    @Value("${redis.pool.minSize:50}")
    private Integer redisPoolMinSize = 50;

    @Value("${redis.pool.maxSize:200}")
    private Integer redisPoolMaxSize = 200;

    @Value("${redis.pool.maxWaitMillis:2000}")
    private Integer redisPoolMaxWaitMillis = 2000;

    @Value("${redis.pool.softMinEvictableIdleTimeMillis:1800000}")
    private Integer redisPoolSoftMinEvictableIdleTimeMillis = 30 * 60 * 1000;

    @Value("${redis.pool.timeBetweenEvictionRunsMillis:60000}")
    private Integer redisPoolBetweenEvictionRunsMillis = 60 * 1000;

    @Bean
    public RedisConnectionFactory redisConnectionFactory(LettuceClientConfiguration clientConfiguration) {

        RedisStandaloneConfiguration standaloneConfiguration = new RedisStandaloneConfiguration();
        standaloneConfiguration.setHostName(redisHost);
        standaloneConfiguration.setPort(redisPort);
        standaloneConfiguration.setDatabase(redisDatabase);
        standaloneConfiguration.setPassword(redisPassword);

        LettuceConnectionFactory connectionFactory = new LettuceConnectionFactory(standaloneConfiguration, clientConfiguration);
        connectionFactory.setDatabase(redisDatabase);
        //关闭共享链接，才能池化生效
        connectionFactory.setShareNativeConnection(false);
        return connectionFactory;
    }

    @Bean
    public LettuceClientConfiguration clientConfiguration() {

        SocketOptions socketOptions = SocketOptions.builder().connectTimeout(Duration.ofMillis(redisConnectTimeout)).build();

        ClientOptions clientOptions = ClientOptions.builder()
                .autoReconnect(true)
                .pingBeforeActivateConnection(true)
                .cancelCommandsOnReconnectFailure(false)
                .disconnectedBehavior(ClientOptions.DisconnectedBehavior.ACCEPT_COMMANDS)
                .socketOptions(socketOptions)
                .build();


        LettucePoolingClientConfiguration clientConfiguration = LettucePoolingClientConfiguration.builder()
                .poolConfig(poolConfig())
                .commandTimeout(Duration.ofMillis(redisReadTimeout))
                .clientOptions(clientOptions)
                .readFrom(ReadFrom.MASTER)
                .build();
        return poolingClientConfiguration;
    }

    private GenericObjectPoolConfig redisPoolConfig() {
        GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
        //连接池的最小连接数
        poolConfig.setMinIdle(redisPoolMinSize);
        //连接池的最大空闲连接数
        poolConfig.setMaxIdle(redisPoolMaxSize);
        //连接池的最大连接数
        poolConfig.setMaxTotal(redisPoolMaxSize);
        //连接池耗尽后是否需要等待，默认true表示等待。当值为true时，setMaxWait才会生效
        poolConfig.setBlockWhenExhausted(true);
        //连接池耗尽后获取连接的最大等待时间，默认-1表示一直等待
        poolConfig.setMaxWait(Duration.ofMillis(redisPoolMaxWaitMillis));
        //创建连接时校验有效性(ping)，默认false
        poolConfig.setTestOnCreate(false);
        //获取连接时校验有效性(ping)，默认false，业务量大时建议设置为false减少开销
        poolConfig.setTestOnBorrow(true);
        //归还连接时校验有效性(ping)，默认false，业务量大时建议设置为false减少开销
        poolConfig.setTestOnReturn(false);
        //是否开启空闲连接检测，如为false，则不剔除空闲连接
        poolConfig.setTestWhileIdle(true);
        //连接空闲多久后逐出，当空闲时间>该值，并且空闲连接>最大空闲数时直接逐出
        poolConfig.setSoftMinEvictableIdleTime(Duration.ofMillis(redisPoolSoftMinEvictableIdleTimeMillis));
        //关闭根据MinEvictableIdleTimeMillis判断逐出
        poolConfig.setMinEvictableIdleTime(Duration.ofMillis(-1));
        //空闲连接逐出的检测周期，默认为60s
        poolConfig.setTimeBetweenEvictionRuns(Duration.ofMillis(redisPoolBetweenEvictionRunsMillis));
        return poolConfig;
    }
}

Cluster集群实例配置

import java.time.Duration;
import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisClusterConfiguration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisNode;
import org.springframework.data.redis.connection.lettuce.LettuceClientConfiguration;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;

import io.lettuce.core.ClientOptions;
import io.lettuce.core.SocketOptions;
import io.lettuce.core.cluster.ClusterClientOptions;
import io.lettuce.core.cluster.ClusterTopologyRefreshOptions;

/**
* Lettuce Cluster 非池化配置，与 application.properties 配置方式二选一
*/
@Configuration
public class RedisConfiguration {

    @Value("${redis.cluster.nodes}")
    private String redisClusterNodes;

    @Value("${redis.cluster.maxDirects:3}")
    private Integer redisClusterMaxDirects;

    @Value("${redis.password:}")
    private String redisPassword;

    @Value("${redis.connect.timeout:2000}")
    private Integer redisConnectTimeout = 2000;

    @Value("${redis.read.timeout:2000}")
    private Integer redisReadTimeout = 2000;

    @Value("${redis.cluster.topology.refresh.period.millis:10000}")
    private Integer redisClusterTopologyRefreshPeriodMillis = 10000;

    @Bean
    public RedisConnectionFactory redisConnectionFactory(LettuceClientConfiguration clientConfiguration) {

        RedisClusterConfiguration clusterConfiguration = new RedisClusterConfiguration();

        List<RedisNode> clusterNodes = new ArrayList<>();
        for (String clusterNodeStr : redisClusterNodes.split(",")) {
            String[] nodeInfo = clusterNodeStr.split(":");
            clusterNodes.add(new RedisNode(nodeInfo[0], Integer.valueOf(nodeInfo[1])));
        }
        clusterConfiguration.setClusterNodes(clusterNodes);

        clusterConfiguration.setPassword(redisPassword);
        clusterConfiguration.setMaxRedirects(redisClusterMaxDirects);

        LettuceConnectionFactory connectionFactory = new LettuceConnectionFactory(clusterConfiguration, clientConfiguration);
        return connectionFactory;
    }

    @Bean
    public LettuceClientConfiguration clientConfiguration() {

        SocketOptions socketOptions = SocketOptions.builder().connectTimeout(Duration.ofMillis(redisConnectTimeout)).build();

        ClusterTopologyRefreshOptions topologyRefreshOptions = ClusterTopologyRefreshOptions.builder()
                .enableAllAdaptiveRefreshTriggers()
                .enablePeriodicRefresh(Duration.ofMillis(redisClusterTopologyRefreshPeriodMillis))
                .build();

        ClusterClientOptions clientOptions = ClusterClientOptions.builder()
                .autoReconnect(true)
                .pingBeforeActivateConnection(true)
                .cancelCommandsOnReconnectFailure(false)
                .disconnectedBehavior(ClientOptions.DisconnectedBehavior.ACCEPT_COMMANDS)
                .socketOptions(socketOptions)
                .topologyRefreshOptions(topologyRefreshOptions)
                .build();


        LettuceClientConfiguration clientConfiguration = LettuceClientConfiguration.builder()
                .commandTimeout(Duration.ofMillis(redisReadTimeout))
                .readFrom(ReadFrom.MASTER)
                .clientOptions(clientOptions)
                .build();
        return clientConfiguration;
    }
}

Cluster实例池化配置

引入池化组件

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-pool2</artifactId>
    <version>2.11.1</version>
</dependency>

代码配置

import java.time.Duration;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisClusterConfiguration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisNode;
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 io.lettuce.core.ClientOptions;
import io.lettuce.core.SocketOptions;
import io.lettuce.core.cluster.ClusterClientOptions;
import io.lettuce.core.cluster.ClusterTopologyRefreshOptions;

/**
* Lettuce 池化配置
*/
@Configuration
public class RedisPoolConfiguration {

    @Value("${redis.cluster.nodes}")
    private String redisClusterNodes;

    @Value("${redis.cluster.maxDirects:3}")
    private Integer redisClusterMaxDirects;

    @Value("${redis.password:}")
    private String redisPassword;

    @Value("${redis.connect.timeout:2000}")
    private Integer redisConnectTimeout = 2000;

    @Value("${redis.read.timeout:2000}")
    private Integer redisReadTimeout = 2000;

    @Value("${redis.cluster.topology.refresh.period.millis:10000}")
    private Integer redisClusterTopologyRefreshPeriodMillis = 10000;

    @Value("${redis.pool.minSize:50}")
    private Integer redisPoolMinSize = 50;

    @Value("${redis.pool.maxSize:200}")
    private Integer redisPoolMaxSize = 200;

    @Value("${redis.pool.maxWaitMillis:2000}")
    private Integer redisPoolMaxWaitMillis = 2000;

    @Value("${redis.pool.softMinEvictableIdleTimeMillis:1800000}")
    private Integer redisPoolSoftMinEvictableIdleTimeMillis = 30 * 60 * 1000;

    @Value("${redis.pool.timeBetweenEvictionRunsMillis:60000}")
    private Integer redisPoolBetweenEvictionRunsMillis = 60 * 1000;

    @Bean
    public RedisConnectionFactory redisConnectionFactory(LettuceClientConfiguration clientConfiguration) {

        RedisClusterConfiguration clusterConfiguration = new RedisClusterConfiguration();

        List<RedisNode> clusterNodes = new ArrayList<>();
        for (String clusterNodeStr : redisClusterNodes.split(",")) {
            String[] nodeInfo = clusterNodeStr.split(":");
            clusterNodes.add(new RedisNode(nodeInfo[0], Integer.valueOf(nodeInfo[1])));
        }
        clusterConfiguration.setClusterNodes(clusterNodes);

        clusterConfiguration.setPassword(redisPassword);
        clusterConfiguration.setMaxRedirects(redisClusterMaxDirects);

        LettuceConnectionFactory connectionFactory = new LettuceConnectionFactory(clusterConfiguration, clientConfiguration);
        //一定要关闭共享连接，否则连接池将不会生效
        connectionFactory.setShareNativeConnection(false);
        return connectionFactory;
    }

    @Bean
    public LettuceClientConfiguration clientConfiguration() {

        SocketOptions socketOptions = SocketOptions.builder().connectTimeout(Duration.ofMillis(redisConnectTimeout)).build();

        ClusterTopologyRefreshOptions topologyRefreshOptions = ClusterTopologyRefreshOptions.builder()
                .enableAllAdaptiveRefreshTriggers()
                .enablePeriodicRefresh(Duration.ofMillis(redisClusterTopologyRefreshPeriodMillis))
                .build();

        ClusterClientOptions clientOptions = ClusterClientOptions.builder()
                .autoReconnect(true)
                .pingBeforeActivateConnection(true)
                .cancelCommandsOnReconnectFailure(false)
                .disconnectedBehavior(ClientOptions.DisconnectedBehavior.ACCEPT_COMMANDS)
                .socketOptions(socketOptions)
                .topologyRefreshOptions(topologyRefreshOptions)
                .build();


        LettucePoolingClientConfiguration clientConfiguration = LettucePoolingClientConfiguration.builder()
                .poolConfig(poolConfig())
                .commandTimeout(Duration.ofMillis(redisReadTimeout))
                .clientOptions(clientOptions)
                .readFrom(ReadFrom.MASTER)
                .build();
        return clientConfiguration;
    }

    private GenericObjectPoolConfig poolConfig() {
        GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
        //连接池的最小连接数
        poolConfig.setMinIdle(redisPoolMinSize);
        //连接池的最大空闲连接数
        poolConfig.setMaxIdle(redisPoolMaxSize);
        //连接池的最大连接数
        poolConfig.setMaxTotal(redisPoolMaxSize);
        //连接池耗尽后是否需要等待, 默认true表示等待. 当值为true时, setMaxWait才会生效
        poolConfig.setBlockWhenExhausted(true);
        //连接池耗尽后获取连接的最大等待时间, 默认-1表示一直等待
        poolConfig.setMaxWait(Duration.ofMillis(redisPoolMaxWaitMillis));
        //创建连接时校验有效性(ping)，默认false
        poolConfig.setTestOnCreate(false);
        //获取连接时校验有效性(ping), 默认false, 业务量大时建议设置为false减少开销
        poolConfig.setTestOnBorrow(true);
        //归还连接时校验有效性(ping)，默认false, 业务量大时建议设置为false减少开销
        poolConfig.setTestOnReturn(false);
        //是否开启空闲连接检测，如为false，则不剔除空闲连接
        poolConfig.setTestWhileIdle(true);
        //禁止最小空闲时间关闭连接
        poolConfig.setMinEvictableIdleTime(Duration.ofMillis(-1));
        //连接空闲多久后逐出，当空闲时间>该值，并且空闲连接>最大空闲数时直接逐出，不再根据MinEvictableIdleTimeMillis判断（默认逐出策略）
        poolConfig.setSoftMinEvictableIdleTime(Duration.ofMillis(redisPoolSoftMinEvictableIdleTimeMillis));
        //空闲连接逐出的检测周期，默认为60s
        poolConfig.setTimeBetweenEvictionRuns(Duration.ofMillis(redisPoolBetweenEvictionRunsMillis));

        return poolConfig;
    }

}

参数明细

表1 LettuceConnectionFactory参数
参数	类型	默认值	说明
configuration	RedisConfiguration	-	redis连接配置，常用两个子类： RedisStandaloneConfiguration RedisClusterConfiguration
clientConfiguration	LettuceClientConfiguration	-	客户端配置参数，常用子类： LettucePoolingClientConfiguration（用于池化）
shareNativeConnection	boolean	true	是否采用共享连接，默认true，采用连接池时必须设置为false

表2 RedisStandaloneConfiguration参数
参数	默认值	说明
hostName	localhost	连接Redis实例的IP地址/域名
port	6379	连接端口号
database	0	数据库下标
password	-	连接密码

表3 RedisClusterConfiguration参数
参数	说明
clusterNodes	cluster节点连接信息，需节点IP、Port
maxRedirects	cluster访问最大重定向次数，建议值：3
password	连接密码

表4 LettuceClientConfiguration参数
参数	类型	默认值	说明
timeout	Duration	60s	命令超时时间配置，建议值：2s
clientOptions	ClientOptions	-	配置项
readFrom	readFrom	MASTER	读取模式，建议值：MASTER，其余配置在发生故障切换场景下，均存在访问失败风险

表5 LettucePoolingClientConfiguration参数
参数	类型	默认值	说明
timeout	Duration	60s	命令超时时间配置，建议值：2s
clientOptions	ClientOptions	-	配置项
poolConfig	GenericObjectPoolConfig	-	连接池配置
readFrom	readFrom	MASTER	读取模式，建议值：MASTER，其余配置在发生故障切换场景下，均存在访问失败风险

表6 ClientOptions参数
参数	类型	默认值	说明
autoReconnect	boolean	true	连接断开后，是否自动发起重连，建议值：true
pingBeforeActivateConnection	boolean	true	连接创建后，是否通过ping/pong校验连接可用性，建议值：true
cancelCommandsOnReconnectFailure	boolean	true	连接重连失败时，是否取消队列中的命令，建议值：false
disconnectedBehavior	DisconnectedBehavior	DisconnectedBehavior.DEFAULT	连接断开时的行为，建议值：ACCEPT_COMMANDS DEFAULT：当autoReconnect为true时，允许命令进入队列等待，当autoReconnect为false时，禁止命令进入队列等待 ACCEPT_COMMANDS：允许命令进入队列等待 REJECT_COMMANDS：禁止命令进入队列等待
socketOptions	SocketOptions	-	网络配置项

表7 SocketOptions参数
参数	默认值	说明
connectTimeout	10s	连接超时时间配置，建议值：2s

表8 GenericObjectPoolConfig参数
参数	默认值	说明
minIdle	-	连接池的最小连接数
maxIdle	-	连接池的最大空闲连接数
maxTotal	-	连接池的最大连接数
blockWhenExhausted	true	连接池耗尽后是否需要等待，默认true表示等待。当值为true时，设置maxWaitMillis才会生效
maxWaitMillis	-1	连接池耗尽后获取连接的最大等待时间，默认-1表示一直等待
testOnCreate	false	创建连接时校验有效性(ping)，默认false
testOnBorrow	false	获取连接时校验有效性(ping)，默认false，业务量大时建议设置为false减少开销
testOnReturn	false	归还连接时校验有效性(ping)，默认false，业务量大时建议设置为false减少开销
testWhileIdle	false	是否开启空闲连接检测，如为false，则不剔除空闲连接，建议值：true
softMinEvictableIdleTimeMillis	1800000	连接空闲多久后逐出，（空闲时间>该值 && 空闲连接>最大空闲数）时直接逐出
minEvictableIdleTimeMillis	60000	根据minEvictableIdleTimeMillis判断逐出，建议值：-1，关闭该策略，改用softMinEvictableIdleTimeMillis策略
timeBetweenEvictionRunsMillis	60000	空闲连接逐出的检测周期，单位：毫秒

DCS实例配置建议

连接池化
 因lettuce底层采用基于netty的NIO模式，和redis server进行通信，不同于jedis的BIO模式。底层采用长连接 + 队列的组合模式，借助TCP顺序发、顺序收的特性，来实现同时处理多请求发送和多响应接收，单条连接可支撑的QPS在3K~5K不等，线上系统建议不要超过3K。lettuce本身不支持池化，且在springboot中默认不开启池化，如需开启池化，需通过手动引入commons-pool2组件，并关闭LettuceConnectionFactory.shareNativeConnection（共享连接）来实现池化。

因每条lettuce连接默认需要配置两个线程池-I/O thread pools、computation thread pool，用于支撑IO事件读取和异步event处理，如配置成连接池形式使用，每个连接都将会创建两个线程池，对内存资源的占用偏高。鉴于lettuce的底层模型实现，及单连接突出的处理能力，不建议通过池化的方式使用lettuce。

拓扑刷新

在连接cluster类型实例中，lettuce会在初始化时，向配置的节点列表随机发送cluster nodes来获取集群slot的分布信息。如后续cluster扩/缩容、主备切换等，会导致集群拓扑结构发生变化，lettuce默认是不感知的，需手动开启主动感知拓扑结构变化，如下：

基于application.properties配置

# 开启自适应拓扑刷新
spring.redis.lettuce.cluster.refresh.adaptive=true
# 开启每10s定时刷新拓扑结构
spring.redis.lettuce.cluster.refresh.period=10S

基于API配置

ClusterTopologyRefreshOptions topologyRefreshOptions = ClusterTopologyRefreshOptions.builder()
    .enableAllAdaptiveRefreshTriggers()
    .enablePeriodicRefresh(Duration.ofMillis(redisClusterTopologyRefreshPeriodMillis))
    .build();

ClusterClientOptions clientOptions = ClusterClientOptions.builder()
        ...
        ...
        .topologyRefreshOptions(topologyRefreshOptions)
        .build();

爆炸半径
 因lettuce底层采用的是单长连接 + 请求队列的组合模式，一旦遇到网络抖动/闪断，或连接失活，将影响所有请求，尤其是在连接失活场景中，将尝试tcp重传，直至重传超时关闭连接，待连接重建后才能恢复。在重传期间请求队列会不断堆积请求，上层业务非常容易出现批量超时，甚至在部分操作系统内核中的重传超时配置过长，致使业务系统长时间处于不可用状态。因此，不推荐使用lettuce组件，建议用jedis组件替换。

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