[CURATOR-355] Curator client fails when connecting to read-only ensemble

ZK is 3.5.1-alpha

I have a 3 nodes ZK cluster , readonly mode is enabled.

2 nodes are down, so one of them (QA-E8WIN11) is in read-only (verified by using the ZK API manually). All the machines of the ensemble can be pinged from the client.

I'm using this piece of code:

		Builder curatorClientBuilder = CuratorFrameworkFactory.builder()

				.connectString("QA-E8WIN11:2181,QA-E8WIN12:2181")

				.sessionTimeoutMs(45000).connectionTimeoutMs(15000)

				.retryPolicy(new RetryNTimes(3, 5000)).canBeReadOnly(true);


		CuratorFramework client = curatorClientBuilder.build();

		client.start();

		client.getZookeeperClient().blockUntilConnectedOrTimedOut();

		System.out.println("Successfully established the connection with ZooKeeper");

		

		client.getData().forPath("/");

		System.out.println("Done.");

When curator pick the host that is UP first, it goes through very quickly. When it picks the host that is down first (QA-E8WIN12), it seems to be stuck at the getData() call for a very long time, and then eventually fail with a ConnectionLossException. (see attached log)

---
Originally reported by benjamin.jaton, imported from: Curator client fails when connecting to read-only ensemble

• status: Open
  
• priority: Critical
  
• resolution: Unresolved
  
• imported: 2025-01-21