误用.Net Redis客户端工具CSRedisCore，自己挖坑自己填

前导　　

　　上次Redis MQ分布式改造完成之后，编排的容器稳定运行了一个多月，昨天突然收到ETL端同事通知，没有采集到解析日志了。

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赶紧进服务器看了一下，用于数据接收的receiver容器挂掉了，尝试docker container start [containerid], 几分钟后该容器再次崩溃。

Redis连接超限

docker log [containerid] 查看容器日志；重点：CSRedis.RedisException: ERR max number of clients reached

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日志上显示连接Redis服务器的客户端数量超限，头脑快速思考，目前编排的某容器使用CSRedisCore 对于16个Redis DB实例化了16个客户端，但Redis服务器也不至于这么不经折腾吧。

赶紧进redis.io官网搜集相关资料。

After the client is initialized, Redis checks if we are already at the limit of the number of clients that it is possible to handle simultaneously (this is configured using the maxclients configuration directive, see the next section of this document for further information).
In case it can't accept the current client because the maximum number of clients was already accepted, Redis tries to send an error to the client in order to make it aware of this condition, and closes the connection immediately. The error message will be able to reach the client even if the connection is closed immediately by Redis because the new socket output buffer is usually big enough to contain the error, so the kernel will handle the transmission of the error.

大致意思是：Redis服务器maxclients配置了客户端连接数，如果当前连接的客户端超限，Redis会回发一个错误消息给客户端，并迅速关闭客户端连接。

立刻登录Redis服务器查看默认配置，确认当前Redis服务器默认配置是10000。

After the client is initialized, Redis checks if we are already at the limit of the number of clients that it is possible to handle simultaneously (this is configured using the maxclients configuration directive, see the next section of this document for further information).
In case it can't accept the current client because the maximum number of clients was already accepted, Redis tries to send an error to the client in order to make it aware of this condition, and closes the connection immediately. The error message will be able to reach the client even if the connection is closed immediately by Redis because the new socket output buffer is usually big enough to contain the error, so the kernel will handle the transmission of the error.

640?wx_fmt=png 左图表明：通过Redis-Cli 登录进服务器立即就被踢下线。

基本可认定redis客户端使用方式有问题。

CSRedisCore使用方式

　继续查看相关资料，可在redis服务器上利用redis-cli命令：info clients、client list仔细分析客户端连接。

info clients 命令显示现场确实有10000的连接数；

640?wx_fmt=gif client list命令显示连接如下

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官方对client list命令输出字段的解释：
addr: The client address, that is, the client IP and the remote port number it used to connect with the Redis server.
fd: The client socket file descriptor number.
name: The client name as set by CLIENT SETNAME.
age: The number of seconds the connection existed for.
idle: The number of seconds the connection is idle.
flags: The kind of client (N means normal client, check the full list of flags).
omem: The amount of memory used by the client for the output buffer.
cmd: The last executed command.