来自apache kafka文档：
broker.id属性是集群中每个节点的唯一永久名称。
代理id必须是唯一的，因为此值用于核心kafka算法（leader/followers）。
另一方面，每个kafka代理通过zookeeper使用broker.id值注册自己。这是这个值必须是唯一的另一个原因：否则您将得到

java.lang.RuntimeException: A broker is already registered on the path /brokers/ids/0. This probably indicates that you either have configured a brokerid that is already in use, or else you have shutdown this broker and restarted it faster than the zookeeper timeout so it appears to be re-registering.