尝试从 zookeeper 节点获取数据时出现异常：(KeeperErrorCode: ConnectionLoss)

Question

我正在使用以下代码从 zookeeper 中提取 Kafka 代理列表：

private static String getBrokerList() {
        try {
            ZooKeeper zookeeper = new ZooKeeper(zookeeperConnect, 15000, null);
            List<String> ids = zookeeper.getChildren(ZkUtils.BrokerIdsPath(), false);
            List<String> brokerList = new ArrayList<>();
            for (String id : ids) {
                String brokerInfo = new String(zookeeper.getData(ZkUtils.BrokerIdsPath() + '/' + id, false, null), Charset.forName("UTF-8"));
                JsonObject jsonElement = new JsonParser().parse(brokerInfo).getAsJsonObject();
                String host = jsonElement.get("host").getAsString();
                brokerList.add(host + ':' + jsonElement.get("port").toString());
            }
            return Joiner.on(",").join(brokerList);
        } catch (KeeperException | InterruptedException e) {
            Throwables.propagate(e);
        }
        return "";
    }

当一个线程一次执行代码时，上面的代码工作正常。但是，当多个线程正在执行上述代码时，它偶尔会失败并出现以下异常：

Caused by: org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /brokers/ids
    at org.apache.zookeeper.KeeperException.create(KeeperException.java:99)
    at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
    at org.apache.zookeeper.ZooKeeper.getChildren(ZooKeeper.java:1532)
    at org.apache.zookeeper.ZooKeeper.getChildren(ZooKeeper.java:1560)

我在这里做错了什么？我的zookeeper版本是3.4.6-1569965.

Answer 1

来自 http://zookeeper.apache.org/doc/r3.4.9/api/org/apache/zookeeper/ZooKeeper.html#ZooKeeper(java.lang.String,%20int,%20org.apache.zookeeper.Watcher)

"Session establishment is asynchronous. This constructor will initiate connection to the server and return immediately - potentially (usually) before the session is fully established. The watcher argument specifies the watcher that will be notified of any changes in state. This notification can come at any point before or after the constructor call has returned."

您必须等待 zookeeper 连接完全建立： https://www.tutorialspoint.com/zookeeper/zookeeper_quick_guide.htm

向下滚动到 api 部分 "Connect to the ZooKeeper Ensemble"

尝试从 zookeeper 节点获取数据时出现异常：(KeeperErrorCode: ConnectionLoss)

Exception while trying to fetch data from zookeeper node: (KeeperErrorCode: ConnectionLoss )

java

apache-zookeeper