redis - 在集群中选举出新的 master 时恢复连接

Question

我有一个包含 3 个节点的 Redis 集群； 1个是master，另外2个是slave，持有master的副本。当我杀死 master 实例时，Redis Sentinel 将另一个节点提升为 master，它开始接受写入。

在我的测试过程中，我注意到一旦提升了新的 master，Redis 中使用 SE.Redis 的第一个操作就会失败:

StackExchange.Redis.RedisConnectionException: SocketFailure on GET ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

为了避免这种情况，我实现了如下重试逻辑。有没有更好的选择？

private RedisValue RedisGet(string key)
{
    return RedisOperation(() =>
    {
        RedisKey redisKey = key;
        RedisValue redisValue = connection.StringGet(redisKey);
        return (redisValue);
    });
}

private T RedisOperation<T>(Func<T> act)
{
    int timeToSleepBeforeRetryInMiliseconds = 20;
    DateTime startTime = DateTime.Now;

    while (true)
    {
        try
        {
            return act();
        }
        catch (Exception e)
        {
            Debug.WriteLine("Failed to perform REDIS OP");

            TimeSpan passedTime = DateTime.Now - startTime;
            if (this.retryTimeout < passedTime)
            {
                Debug.WriteLine("ABORTING re-try to REDIS OP");
                throw;
            }
            else
            {
                int remainingTimeout = (int)(this.retryTimeout.TotalMilliseconds - passedTime.TotalMilliseconds);
                // if remaining time is less than 1 sec than wait only for that much time and than give a last try
                if (remainingTimeout < timeToSleepBeforeRetryInMiliseconds)
                {
                    timeToSleepBeforeRetryInMiliseconds = remainingTimeout;
                }
            }

            Debug.WriteLine("Sleeping " + timeToSleepBeforeRetryInMiliseconds + " before next try");
            System.Threading.Thread.Sleep(timeToSleepBeforeRetryInMiliseconds);
        }
    }
}

Answer 1

TLDR:不要将 Sentinel 与 Stackexchange.Redis 一起使用，因为此客户端库中仍未实现 Sentinel 支持。

参见 https://github.com/StackExchange/StackExchange.Redis/labels/sentinel对于所有 Unresolved 问题，还有一个相当不错的 PR 开放了大约 1 年。

话虽如此，我在重试方面也有相对较好的经验，但我绝不会在生产中使用这种方法，因为它根本不可靠。