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https://issues.apache.org/jira/browse/ZOOKEEPER-2926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16319101#comment-16319101
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Hadoop QA commented on ZOOKEEPER-2926:
--------------------------------------

-1 overall.  GitHub Pull Request  Build
      

    +1 @author.  The patch does not contain any @author tags.

    +1 tests included.  The patch appears to include 26 new or modified tests.

    +1 javadoc.  The javadoc tool did not generate any warning messages.

    +1 javac.  The applied patch does not increase the total number of javac 
compiler warnings.

    +1 findbugs.  The patch does not introduce any new Findbugs (version 3.0.1) 
warnings.

    +1 release audit.  The applied patch does not increase the total number of 
release audit warnings.

    -1 core tests.  The patch failed core unit tests.

    +1 contrib tests.  The patch passed contrib unit tests.

Test results: 
https://builds.apache.org/job/PreCommit-ZOOKEEPER-github-pr-build/1403//testReport/
Findbugs warnings: 
https://builds.apache.org/job/PreCommit-ZOOKEEPER-github-pr-build/1403//artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Console output: 
https://builds.apache.org/job/PreCommit-ZOOKEEPER-github-pr-build/1403//console

This message is automatically generated.

> Data inconsistency issue due to the flaw in the session management
> ------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-2926
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2926
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: server
>    Affects Versions: 3.5.3, 3.6.0
>            Reporter: Fangmin Lv
>            Priority: Critical
>
> The local session upgrading feature will upgrade the session locally before 
> receving a quorum commit of creating global session. It's possible that the 
> server shutdown before the creating session request being sent to leader, if 
> we retained the ZKDatabase or there is Snapshot happened just before 
> shutdown, then only this server will have the global session. 
> If that server didn't become leader, then it will have more global sessions 
> than others, and those global sessions won't expire as the leader doesn't 
> know it's existence. If the server became leader, it will accept the client 
> renew session request and the client is allowed to create ephemeral nodes, 
> which means other servers only have ephemeral nodes but not that global 
> session. If there is follower going to have SNAP sync with it, then it will 
> also have the global session. If the server without that global session 
> becomes new leader, it will check and delete those dangling ephemeral node 
> before serving traffic. These could introduce the issues that the ephemeral 
> node being exist on some servers but not others. 
> There is dangling global session issue even without local session feature, 
> because on leader it will update the ZKDatabase when processing 
> ConnectionRequest and in the PrepRequestProcessor before it's quorum 
> committed, which also has this risk.



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