nano conf/zoo.cfg   
 
tickTime=2000   
dataDir=/var/lib/zookeeper   
clientPort=2181   
initLimit=5   
syncLimit=2   
server.1=10.0.0.2:2888:3888   
server.2=10.0.0.3:2888:3888   
server.3=10.0.0.4:2888:3888   

我试图理解这个 cfg 文件。 clientPort 用于传入通信，对吗？但是为什么还有两个这样的端口:server.1=10.0.0.2:2888:3888？

请您参考如下方法:

The entries of the form server.X list the servers that make up the ZooKeeper service. When the server starts up, it knows which server it is by looking for the file myid in the data directory. That file has the contains the server number, in ASCII.

Finally, note the two port numbers after each server name: " 2888" and "3888". Peers use the former port to connect to other peers. Such a connection is necessary so that peers can communicate, for example, to agree upon the order of updates. More specifically, a ZooKeeper server uses this port to connect followers to the leader. When a new leader arises, a follower opens a TCP connection to the leader using this port. Because the default leader election also uses TCP, we currently require another port for leader election. This is the second port in the server entry.

引用:- http://zookeeper.apache.org/doc/r3.1.2/zookeeperStarted.html