SpringBoot 集成Redis Lettuce 客户端 blpop命令出现连接超时的解决方案

springboot 2.x 集成了 Letture。项目启动后,开启一个线程在后台不停地 blpop redis的队列list 。一段时间后，出现连接超时的问题。

为什么用blpop命令呢？ 因为BLPOP 是列表的阻塞式(blocking)弹出原语。 它是 LPOP 命令的阻塞版本，当给定列表内没有任何元素可供弹出的时候，连接将被BLPOP 命令阻塞，直到等待超时或发现可弹出元素为止。 当给定多个 key 参数时，按参数 key的先后顺序依次检查各个列表，弹出第一个非空列表的头元素。

项目启动一段时间后，(大概1分钟)吧。emmemem,抛出以下异常

io.lettuce.core.RedisCommandTimeoutException: Command timed out after 1 minute(s)
    at io.lettuce.core.internal.ExceptionFactory.createTimeoutException(ExceptionFactory.java:53)
    at io.lettuce.core.internal.Futures.awaitOrCancel(Futures.java:246)
    at io.lettuce.core.FutureSyncInvocationHandler.handleInvocation(FutureSyncInvocationHandler.java:75)
    at io.lettuce.core.internal.AbstractInvocationHandler.invoke(AbstractInvocationHandler.java:80)
    at com.sun.proxy.$Proxy191.blpop(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at io.lettuce.core.support.ConnectionWrapping$DelegateCloseToConnectionInvocationHandler.handleInvocation(ConnectionWrapping.java:215)
    at io.lettuce.core.internal.AbstractInvocationHandler.invoke(AbstractInvocationHandler.java:80)
    at com.sun.proxy.$Proxy191.blpop(Unknown Source)
    at com.fish.pro.framework.core.utils.RedisUtil.blpop(RedisUtil.java:787)
    at com.fish.pro.infrastructure.queue.redis.RedisQueue.run(RedisQueue.java:41)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)

源代码片段

public static void init(String host, int port, int database, String password, int minIdle, int maxIdle, int maxTotal) throws Exception {

       GenericObjectPoolConfig genericObjectPoolConfig = new GenericObjectPoolConfig();
       genericObjectPoolConfig.setMaxIdle(maxIdle);
       genericObjectPoolConfig.setMinIdle(minIdle);
       genericObjectPoolConfig.setMaxTotal(maxTotal);
       
       RedisURI uri = 
       RedisURI.builder().withHost(host).withPort(port).withDatabase(database)
       .withPassword(password.toCharArray()).build();
      
       RedisClient client = RedisClient.create(uri);
       GenericObjectPool> pool = 
       ConnectionPoolSupport.createGenericObjectPool(() -> client.connect(),genericObjectPoolConfig);
       pool.preparePool();
        
       RedisUtil.init(pool);
}

 public static  T blpop(String key,Class clazz) {
        
        StatefulRedisConnection connection = null;
        try {
            connection = pool.borrowObject();
            RedisCommands commands = connection.sync();
            KeyValue keyValue = commands.blpop(0, key);
            T obj = JSONUtil.parseObject(keyValue.getValue(), clazz);
            return obj;
        } catch (Exception e) {
            log.error("RedisUtil get exceptions", e);
        } finally {
            close(connection);
        }
        return null;
  }

查阅官网给出的解释：
The configured command timeout applies without considering command-specific timeouts.
翻译过来的意思:配置的命令超时不考虑特定命令的超时。

官网 给出的解决方案：

There are various options:

1. Configure a higher default timeout.

2. Consider a timeout that meets the default timeout when calling blocking commands.

3. Configure TimeoutOptions with a custom TimeoutSource

TimeoutOptions timeoutOptions = TimeoutOptions.builder().timeoutSource(new TimeoutSource() { @Override public long getTimeout(RedisCommand command) { if (command.getType() == CommandType.BLPOP) { return TimeUnit.MILLISECONDS.tonanos(CommandArgsAccessor.getFirstInteger(command.getArgs())); } // -1 indicates fallback to the default timeout return -1; } }).build();

结合官网给出的解决方案， 最终把代码修改为

 public static void init(String host, int port, int database, String password, int minIdle, int maxIdle, int maxTotal) throws Exception {
        TimeoutOptions timeoutOptions = TimeoutOptions.builder().timeoutSource(new TimeoutOptions.TimeoutSource() {
            @Override
            public long getTimeout(RedisCommand command) {

                if (command.getType() == CommandType.BLPOP) {
                    return TimeUnit.MILLISECONDS.tonanos(CommandArgsAccessor.getFirstInteger(command.getArgs()));
                }
                // -1 indicates fallback to the default timeout
                return -1;
            }
        }).build();

        ClientOptions clientOptions = ClientOptions.builder().timeoutOptions(timeoutOptions).build();

        GenericObjectPoolConfig genericObjectPoolConfig = new GenericObjectPoolConfig();
        genericObjectPoolConfig.setMaxIdle(maxIdle);
        genericObjectPoolConfig.setMinIdle(minIdle);
        genericObjectPoolConfig.setMaxTotal(maxTotal);
        RedisURI uri = RedisURI.builder().withHost(host).withPort(port).withDatabase(database).withPassword(password.toCharArray()).build();
        RedisClient client = RedisClient.create(uri);

        //解决阻塞BLPOP超时的问题或直接设置 client.setDefaultTimeout(Duration.ZERO)
        client.setOptions(clientOptions);

        GenericObjectPool> pool = ConnectionPoolSupport.createGenericObjectPool(() -> client.connect(), genericObjectPoolConfig);
        pool.preparePool();
        RedisUtil.init(pool);

    }

修改后，暂没有发现 连接超时现象出现。如有问题，请指导修正~