RedisResponseException：No more data & Zero length respose

运维切换了新的 *Redis* 架构之后，偶尔会报 *No more data* 或 *Zero length respose* 的错误。

### 架构

客户端 C# 使用的 *ServiceStack.Redis 3.9.60.0* 包，通过连接池 `PooledRedisClientManager` 管理连接；
*Redis* 是一主多从；
中间通过 *HAproxy* 代理，实现LB；

### 异常信息

#### 客户端

```cs
ServiceStack.Redis.RedisResponseException
No more data, sPort: 53059, LastCommand:
ServiceStack.Redis
   在 ServiceStack.Redis.RedisNativeClient.CreateResponseError(String error)
   在 ServiceStack.Redis.RedisNativeClient.ExpectSuccess()
   在 ServiceStack.Redis.RedisNativeClient.Set(String key, Byte[] value)
   在 ServiceStack.Redis.RedisClient.Set[T](String key, T value)
   在 ServiceStack.Redis.RedisClient.Set[T](String key, T value, DateTime expiresAt)
   在 Framework.Utils.RedisProvider.Set[T](String key, T value, Int32 minutes)
   在 MX.OBP.WebApp.Login.InitPage()
   在 System.Web.UI.Control.LoadRecursive()
   在 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
```

```cs
ServiceStack.Redis.RedisResponseException
Zero length respose, sPort: 52673, LastCommand:
ServiceStack.Redis
   在 ServiceStack.Redis.RedisNativeClient.CreateResponseError(String error)
   在 ServiceStack.Redis.RedisNativeClient.ParseSingleLine(String r)
   在 ServiceStack.Redis.RedisNativeClient.GetBytes(String key)
   在 ServiceStack.Redis.RedisClient.Get[T](String key)
   在 Framework.Utils.RedisProvider.Get[T](String key)
```

#### HAProxy

查看 *HAProxy* 的日志，对应上面的客户端的出错信息，日志能看到 **cD** 和 **CD** 错误状态。

> CD
> The client unexpectedly aborted during data transfer.
> This can be caused by a browser crash, by an intermediate equipment between the client and haproxy which decided to actively break the connection,
> by network routing issues between the client and haproxy, or by a keep-alive session between the server and the client terminated first by the client.
> 当传输数据时客户端异常退出
>
> cD
> The client did not send nor acknowledge any data for as long as the timeout client delay.
> This is often caused by network failures on client side, or the client simply leaving the net uncleanly.
> 在data阶段，客户端超时

### ServiceStack.Redis 源码

下面贴出了上面错误消息中调用的部分源码，可以看出不管是保存还是获取，在返回的 `Bstream` 中没有值时，就会报上面的错误。

*RedisNativeClient.cs*

```cs
namespace ServiceStack.Redis
{
  public class RedisNativeClient : IRedisNativeClient, IDisposable
  {
    public void Set(string key, byte[] value)
    {
      if (key == null)
        throw new ArgumentNullException(nameof (key));
      value = value ?? new byte[0];
      if (value.Length > 1073741824)
        throw new ArgumentException("value exceeds 1G", nameof (value));
      this.SendExpectSuccess(Commands.Set, key.ToUtf8Bytes(), value);
    }

protected void SendExpectSuccess(params byte[][] cmdWithBinaryArgs)
    {
      if (!this.SendCommand(cmdWithBinaryArgs))
        throw this.CreateConnectionError();
      if (this.Pipeline != null)
        this.Pipeline.CompleteVoidQueuedCommand(new Action(this.ExpectSuccess));
      else
        this.ExpectSuccess();
    }

protected void ExpectSuccess()
    {
      int num = this.SafeReadByte();
      if (num == -1)
        throw this.CreateResponseError("No more data");
      string str = this.ReadLine();
      if (num == 45)
        throw this.CreateResponseError(!str.StartsWith("ERR") || str.Length < 4 ? str : str.Substring(4));
    }

public byte[] GetBytes(string key)
    {
      if (key == null)
        throw new ArgumentNullException(nameof (key));
      return this.SendExpectData(Commands.Get, key.ToUtf8Bytes());
    }

protected byte[] SendExpectData(params byte[][] cmdWithBinaryArgs)
    {
      if (!this.SendCommand(cmdWithBinaryArgs))
        throw this.CreateConnectionError();
      if (this.Pipeline == null)
        return this.ReadData();
      this.Pipeline.CompleteBytesQueuedCommand(new Func<byte[]>(this.ReadData));
      return (byte[]) null;
    }

private byte[] ReadData()
    {
      return this.ParseSingleLine(this.ReadLine());
    }

private byte[] ParseSingleLine(string r)
    {
      if (r.Length == 0)
        throw this.CreateResponseError("Zero length respose");
      switch (r[0])
      {
        case '$':
          if (r == "$-1")
            return (byte[]) null;
          int result;
          if (!int.TryParse(r.Substring(1), out result))
            throw this.CreateResponseError("Invalid length");
          byte[] buffer = new byte[result];
          int offset = 0;
          while (result > 0)
          {
            int num = this.Bstream.Read(buffer, offset, result);
            if (num <= 0)
              throw this.CreateResponseError("Unexpected end of Stream");
            offset += num;
            result -= num;
          }
          if (this.Bstream.ReadByte() != 13 || this.Bstream.ReadByte() != 10)
            throw this.CreateResponseError("Invalid termination");
          return buffer;
        case '-':
          throw this.CreateResponseError(r.StartsWith("-ERR") ? r.Substring(5) : r.Substring(1));
        case ':':
          return r.Substring(1).ToUtf8Bytes();
        default:
          throw this.CreateResponseError("Unexpected reply: " + r);
      }
    }

private int SafeReadByte()
    {
      return this.Bstream.ReadByte();
    }

private RedisResponseException CreateResponseError(string error)
    {
      this.HadExceptions = true;
      RedisResponseException responseException = new RedisResponseException(string.Format("{0}, sPort: {1}, LastCommand: {2}", (object) error, (object) this.clientPort, (object) this.lastCommand));
      RedisNativeClient.log.Error((object) responseException.Message);
      throw responseException;
    }
  }
}
```

### 对策

o(╯□╰)o
因为更改架构之前直连 *Redis* 是正常的，所以猜测是 *HAProxy* 连接 *Redis* 超时导致的。
*Redis* 的超时时间设置的是 5min，*HAProxy* 的超时时间是 10s，所以将 *HAProxy* 的超时时间设为和 *Redis* 一样看看是否有效果。

### 参考

-   [使用ServiceStack.Redis过程中遇到的问题](https://www.cnblogs.com/magialmoon/archive/2012/12/25/2832974.html)
-   [RedisResponseException from BlockingDequeue](https://stackoverflow.com/questions/17453594/redisresponseexception-from-blockingdequeue)
    ```cs
    var redisFactory = new PooledRedisClientManager(redisConn);
    redisFactory.ConnectTimeout = 5;
    redisFactory.IdleTimeOutSecs = 30;
    ```
-   [Redis Mass Insertion](https://redis.io/topics/mass-insert)
-   [Socket.Connect](https://msdn.microsoft.com/zh-cn/library/ych8bz3x(v=vs.110).aspx)
-   [Socket.BeginConnect](https://msdn.microsoft.com/zh-cn/library/tad07yt6(v=vs.110).aspx)
-   [BufferedStream.ReadByte](https://msdn.microsoft.com/zh-cn/library/system.io.bufferedstream.readbyte(v=vs.100).aspx)
-   [Protocol errors, “no more data” errors, “Zero length response” errors while using servicestack.redis in a high volume scenario](https://stackoverflow.com/questions/27929192/protocol-errors-no-more-data-errors-zero-length-response-errors-while-usin)
-   [haproxy状态总结(官方文档加翻译),读haproxy日志必备](https://wenku.baidu.com/view/37021f396bd97f192279e92b.html)

RedisResponseException：No more data & Zero length respose

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