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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2021/05/03 10:43:00 UTC
[jira] [Work logged] (HIVE-24713) HS2 never knows deregistering
from Zookeeper in the particular case
[ https://issues.apache.org/jira/browse/HIVE-24713?focusedWorklogId=592109&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-592109 ]
ASF GitHub Bot logged work on HIVE-24713:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 03/May/21 10:42
Start Date: 03/May/21 10:42
Worklog Time Spent: 10m
Work Description: EugeneChung commented on pull request #1932:
URL: https://github.com/apache/hive/pull/1932#issuecomment-831178569
As indicated by Apache curator, https://github.com/apache/curator/blob/2b68d13f6d1e57e019ee19f96f047361c8b88516/curator-recipes/src/main/java/org/apache/curator/framework/recipes/nodes/PersistentNode.java#L81-L81 ,
DeregisterWatcher must be registered again for any NodeDataChanged events.
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Issue Time Tracking
-------------------
Worklog Id: (was: 592109)
Time Spent: 1.5h (was: 1h 20m)
> HS2 never knows deregistering from Zookeeper in the particular case
> -------------------------------------------------------------------
>
> Key: HIVE-24713
> URL: https://issues.apache.org/jira/browse/HIVE-24713
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Reporter: Eugene Chung
> Assignee: Eugene Chung
> Priority: Major
> Labels: pull-request-available
> Fix For: 4.0.0
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> While using zookeeper discovery mode, the problem that HS2 never knows deregistering from Zookeeper always happens.
> Reproduction is simple.
> # Find one of the zk servers which holds the DeRegisterWatcher watches of HS2 instances. If the version of ZK server is 3.5.0 or above, it's easily found with [http://zk-server:8080/commands/watches] (ZK AdminServer feature)
> # Check which HS2 instance is watching on the ZK server found at 1, say it's _hs2-of-2_
> # Restart the ZK server found at 1
> # Deregister _hs2-of-2_ with the command
> {noformat}
> hive --service hiveserver2 -deregister hs2-of-2{noformat}
> # _hs2-of-2_ never knows that it must be shut down because the watch event of DeregisterWatcher was already fired at the time of 3.
> The reason of the problem is explained at [https://zookeeper.apache.org/doc/r3.3.3/zookeeperProgrammers.html#sc_WatchRememberThese]
> I added some logging to DeRegisterWatcher and checked what events were occurred at the time of 3(restarting of ZK server);
> # WatchedEvent state:Disconnected type:None path:null
> # WatchedEvent[WatchedEvent state:SyncConnected type:None path:null]
> # WatchedEvent[WatchedEvent state:SaslAuthenticated type:None path:null]
> # WatchedEvent[WatchedEvent state:SyncConnected type:NodeDataChanged
> path:/hiveserver2/serverUri=hs2-of-2:10000;version=3.1.2;sequence=0000000711]
> As the zk manual says, watches are one-time triggers. When the connection to the ZK server was reestablished, state:SyncConnected type:NodeDataChanged for the path is fired and it's the end. *DeregisterWatcher must be registered again for the same znode to get a future NodeDeleted event.*
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