【Linux-zookeeper】Unable to read

内部维护一个zookeeper集群，近期有用户反馈集群不稳定，导致业务侧有波动。根据用户提供的IP定位到异常并提供了解决方案。

具体异常：

2018-03-20 23:34:01,887 [myid:99] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@197] - Accepted socket connection from /10.121.82.229:33749
2018-03-20 23:34:01,887 [myid:99] - WARN  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@793] - Connection request from old client /10.121.82.229:33749; will be dropped if server is in r-o mode
2018-03-20 23:34:01,887 [myid:99] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@839] - Client attempting to establish new session at /10.121.82.229:33749
2018-03-20 23:34:01,890 [myid:99] - INFO  [CommitProcessor:99:ZooKeeperServer@595] - Established session 0x6362257b44e5068d with negotiated timeout 10000 for client /10.121.82.229:33749
2018-03-20 23:34:21,859 [myid:99] - WARN  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@349] - caught end of stream exception
EndOfStreamException: Unable to read additional data from client sessionid 0x6362257b44e5068d, likely client has closed socket
        at org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:220)
        at org.apache.zookeeper.server.NIOServerCnxnFactory.run(NIOServerCnxnFactory.java:208)
        at java.lang.Thread.run(Thread.java:745)
2018-03-20 23:34:21,860 [myid:99] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@1001] - Closed socket connection for client /10.121.82.229:33749 which had sessionid 0x6362257b44e5068d

核心报错信息：

EndOfStreamException: Unable to read additional data from client sessionid 0x6362257b44e5068d, likely client has closed socket

具体问题所在：

客户端连接Zookeeper时，配置的超时时长过短。致使Zookeeper还没有读完Consumer的数据，连接就被Consumer断开了。

解决方案：

初始化Zookeeper连接时，将接收超时参数值调整大一些即可，默认是毫秒（ms）
在C++中，在设置第三个参数recv_timeout时，设置大一些，比如10000ms就可以解决这里的问题。

zhandle_t *zookeeper_init(const char *host, watcher_fn fn, int recv_timeout, const clientid_t *clientid, void *context, int flags)