redis multiplexing机制类似http2，在存在并发请求时能减少大量通讯延迟，但不支持blocking相关的操作，如BLPOP

配置 RedisTemplate

RedisTemplate自动根据操作类型，选择是在单连接上进行多路复用，还是申请新的连接/等待空闲连接

@Configuration
public class RedisTemplateConfig {@Beanpublic LettuceConnectionFactory lettuceConnectionFactory(@Value("${redis.cluster}") String address,@Value("${redis.password}") String password) {// 配置连接池管理var poolConfig = new GenericObjectPoolConfig<StatefulRedisClusterConnection<String, String>>();poolConfig.setMaxTotal(20);poolConfig.setMaxIdle(20);poolConfig.setMinIdle(2);poolConfig.setTestWhileIdle(true);poolConfig.setMinEvictableIdleDuration(Duration.ofMillis(60000));poolConfig.setTimeBetweenEvictionRuns(Duration.ofMillis(30000));poolConfig.setNumTestsPerEvictionRun(-1);// 配置客户端行为var clientConfig = LettucePoolingClientConfiguration.builder().clientOptions(ClusterClientOptions.builder().autoReconnect(true).pingBeforeActivateConnection(true).socketOptions(SocketOptions.builder().connectTimeout(Duration.ofSeconds(3)).build()).timeoutOptions(TimeoutOptions.builder().fixedTimeout(Duration.ofSeconds(3)).build()).topologyRefreshOptions(ClusterTopologyRefreshOptions.builder().enableAdaptiveRefreshTrigger(RefreshTrigger.MOVED_REDIRECT,RefreshTrigger.PERSISTENT_RECONNECTS).adaptiveRefreshTriggersTimeout(Duration.ofSeconds(30)).build()).build()).poolConfig(poolConfig).build();// 配置集群连接信息var redisConfig = new RedisClusterConfiguration();redisConfig.setMaxRedirects(5);redisConfig.setPassword(password);String[] serverArray = address.split(",|，|;|；");// 获取服务器数组Set<RedisNode> nodes = new HashSet<>();for (String ipPort : serverArray) {nodes.add(RedisNode.fromString(ipPort));}redisConfig.setClusterNodes(nodes);return new LettuceConnectionFactory(redisConfig, clientConfig);}@Beanpublic StringRedisTemplate redisTemplate(LettuceConnectionFactory lettuceConnectionFactory) {return new StringRedisTemplate(lettuceConnectionFactory);}
}

验证blocking操作在独立连接上进行

实现blocking LPOP操作的方法在opsForList()里；
并发100压测期间查看客户端本地的tcp连接，可以看到和每个redis节点都建立了大量连接；
证明RedisTemplate没有选择让不同并发线程共用同一个StatefulConnection

    @Testpublic void blpop() throws Exception {long start = System.currentTimeMillis();AtomicLong err = new AtomicLong();int maxThreads = 100;Semaphore semaphore = new Semaphore(maxThreads);for (int i = 0; i < maxThreads; i++) {final int threadnum = i + 1;semaphore.acquire(1);new Thread(new Runnable() {@Overridepublic void run() {try {template.opsForList().leftPop("test" + threadnum, 2, TimeUnit.SECONDS);} catch (Exception ex) {log.error("leftPop", ex);err.addAndGet(1L);} finally {semaphore.release(1);}}}).start();}semaphore.acquire(maxThreads);long end = System.currentTimeMillis();log.info("耗时{}ms, 错误{}", end - start, err.get());}

验证单tcp连接的多路复用

发起100个线程，每个线程连续进行1000次读写操作；
执行期间查看客户端本地的tcp连接，可以看到只建立了一个和redis节点的连接；
每个线程的指令并发地在同一个tcp连接上发出和响应，一次请求+响应实际相当于http2的一路stream

@Slf4j
@EnableAutoConfiguration(exclude = { RedisAutoConfiguration.class })
@SpringBootTest(classes = { RedisTemplateConfig.class })
public class RedisTemplateTest {@AutowiredStringRedisTemplate template;@Testpublic void getSet() throws Exception {long start = System.currentTimeMillis();int maxThreads = 100;long maxMessagess = 1000;AtomicLong err = new AtomicLong();AtomicLong num = new AtomicLong();Semaphore semaphore = new Semaphore(maxThreads);for (int i = 0; i < maxThreads; i++) {final int threadnum = i + 1;semaphore.acquire(1);new Thread(new Runnable() {@Overridepublic void run() {int j = 0;try {for (; j < maxMessagess; j++) {String key = "thread" + threadnum + "test" + j;String value = "test" + j;template.opsForValue().set(key, value, 1, TimeUnit.SECONDS);assertEquals(value, template.opsForValue().get(key));}} finally {num.addAndGet(j);semaphore.release(1);}}}).start();}semaphore.acquire(maxThreads);long end = System.currentTimeMillis();double rate = 1000d * num.get() / (end - start);log.info("每秒发送并读取消息{}; 耗时{}ms, 累计发送{}", rate, end - start, num.get());}

RedisTemplate屏蔽了哪些并发命令可以共用连接的决策难点，所以不要自行使用Lettuce客户端获取连接或从连接池申请连接。