使用curator在zookeeper中创建一个ttl节点

Question

How to create a ttl node using apache curator? I have tried the following

ExponentialBackoffRetry retryPolicy = new ExponentialBackoffRetry(1000, 3);
        String connectionString = "127.0.0.1:2181";
        CuratorFramework client = CuratorFrameworkFactory.newClient(connectionString, retryPolicy);
        client.getUnhandledErrorListenable().addListener((message, e) -> {
            System.err.println("error=" + message);
            e.printStackTrace();
        });
        client.getConnectionStateListenable().addListener((c, newState) -> {
            System.out.println("state=" + newState);
        });
        client.start();

Code 1:

PersistentTtlNode persistentTtlNode = new PersistentTtlNode(client, "/stores/abc.com", 10000, "".getBytes());
        persistentTtlNode.start();
        boolean flag = persistentTtlNode.waitForInitialCreate(1000, TimeUnit.MICROSECONDS);
        System.out.println(flag);
        persistentTtlNode.close();

Result: Node is not getting created and the flag is false

Code 2:

client.create().withTtl(1000).creatingParentContainersIfNeeded().withMode(CreateMode.PERSISTENT_WITH_TTL).forPath("/stores/india.com");

Result: Getting the following exception:

Exception in thread "main" org.apache.zookeeper.KeeperException$UnimplementedException: KeeperErrorCode = Unimplemented for /stores/india.com
    at org.apache.zookeeper.KeeperException.create(KeeperException.java:106)
    at org.apache.zookeeper.KeeperException.create(KeeperException.java:54)
    at org.apache.zookeeper.ZooKeeper.create(ZooKeeper.java:1837)
    at org.apache.curator.framework.imps.CreateBuilderImpl$16.call(CreateBuilderImpl.java:1131)
    at org.apache.curator.framework.imps.CreateBuilderImpl$16.call(CreateBuilderImpl.java:1113)
    at org.apache.curator.RetryLoop.callWithRetry(RetryLoop.java:93)
    at org.apache.curator.framework.imps.CreateBuilderImpl.pathInForeground(CreateBuilderImpl.java:1110)
    at org.apache.curator.framework.imps.CreateBuilderImpl.protectedPathInForeground(CreateBuilderImpl.java:593)
    at org.apache.curator.framework.imps.CreateBuilderImpl.forPath(CreateBuilderImpl.java:583)
    at org.apache.curator.framework.imps.CreateBuilderImpl.forPath(CreateBuilderImpl.java:561)
    at org.apache.curator.framework.imps.CreateBuilderImpl.forPath(CreateBuilderImpl.java:48)
    at Main.main(Main.java:67)

What's the correct way to create a node with ttl in apache curator?

Answer 1

Finally found the answer, apparently we need to enable certain configurations while starting zookeeper.

1. Go to conf directory
2. Create a new file called zoo.cfg
3. Paste the following to the file

tickTime=2000
dataDir=./data/zookeeper
clientPort=2181
maxClientCnxns=60
extendedTypesEnabled=true
emulate353TTLNodes=true

My mistake was I added zookeeper.extendedTypesEnabled in the config file. Don't add the word zookeeper . It's needed only if you are using command line shell ie zkCli.sh .

Now restart the cluster using bin/zkServer.sh stop and bin/zkServer.sh start .

The above commands will work fine without throwing any more exceptions.

Note: If the znode is not modified within the TTL and has no children it will become a candidate to be deleted by the server at some point in the future.

Keep in mind, zookeeper version should be > 3.5.3 and the java client version should be the same as zookeeper version