[jira] [Created] (ZOOKEEPER-4698) Persistent watch events lost after reconnection

2023-05-22 Thread Kezhu Wang (Jira) 
Kezhu Wang created ZOOKEEPER-4698:
-

 Summary: Persistent watch events lost after reconnection
 Key: ZOOKEEPER-4698
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-4698
 Project: ZooKeeper
  Issue Type: Bug
  Components: server
Affects Versions: 3.8.1, 3.7.1
Reporter: Kezhu Wang


I found this in reply to [apache#1950 
(comment)|https://github.com/apache/zookeeper/pull/1950#issuecomment-1553742525].
 But it turns out a known issue [apache#1106 
(comment)|https://github.com/apache/zookeeper/pull/1106#issuecomment-543860329].

I think it is worth to note separately in jira for potential future discussions 
and fix. I have pushed a [test 
case|https://github.com/kezhuw/zookeeper/commit/31d89e9829380559066fc2b83e3d38462380c5d4]
 for this. It fails as expected.

{noformat}
[ERROR] Failures: 
[ERROR]   WatchEventWhenAutoResetTest.testPersistentRecursiveWatch:237 do not 
receive a NodeDataChanged ==> expected: not 
[ERROR]   WatchEventWhenAutoResetTest.testPersistentWatch:211 do not receive a 
NodeDataChanged ==> expected: not 
{noformat}

It is hard to fix this with sole {{DataTree}}. Two independent comments 
[pointed|https://github.com/apache/zookeeper/pull/1106#issuecomment-1366449561] 
[out|https://github.com/kezhuw/zookeeper/commit/31d89e9829380559066fc2b83e3d38462380c5d4#diff-cfd09b7021c88da6631872e8a4a271f830162f7c5a63a140839ba029048493fdR227-R230]
 this. I guess we have to walk through txn log to deliver a correct fix. 

{quote}
Watches will not be received while disconnected from a server. When a client 
reconnects, any previously registered watches will be reregistered and 
triggered if needed. In general this all occurs transparently. There is one 
case where a watch may be missed: a watch for the existence of a znode not yet 
created will be missed if the znode is created and deleted while disconnected.
{quote}

This is [what our programer's guide 
says|https://zookeeper.apache.org/doc/r3.8.1/zookeeperProgrammers.html#ch_zkWatches].
 It is well-known, at least for me, that we can lose some transiently 
intermediate events in reconnection. But in case of persistent watch, we can 
lose more. This forces clients to rebuild their knowledge on reconnection.



--
This message was sent by Atlassian Jira
(v8.20.10#820010)

Re: Query - Facing

2023-05-22 Thread Enrico Olivelli 
Jeya,

Il Mer 22 Mar 2023, 17:29 Jeyalakshmi Rajagopal 
ha scritto:

> Hi Team,
> I am installing zookeeper -3.8.0 version on my Linux server.
> Zookeeper server has started successfully. But zookeeper status is showing
> as
> below
>
> #./zkServer.sh status
> Zookeeper JMX enabled by default
> Using config: /opt/zookeeper/bin/..conf/zoo.cfg
> myid could not be determined , will not able to locate client port in the
> server configs. Client address:localhost. Client SSL: false.
> Error contacting service.It is probably not running.
>
> But i was keeping the myid in server1 has 1, server2 has 2 and server3 has
> 3 .
>
> I am expecting the leader and 2 followers in zookeeper status .
>
> Could you please help me?
>

I am sorry, I missed this message.
Have you been able to solve your problem?

Enrico


> Thanks & Regards,
> Jeya
>