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https://issues.apache.org/jira/browse/ZOOKEEPER-2926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16550299#comment-16550299
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Hadoop QA commented on ZOOKEEPER-2926:
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+1 overall. GitHub Pull Request Build
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 20 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 passed core unit tests.
+1 contrib tests. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-ZOOKEEPER-github-pr-build/1974//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-ZOOKEEPER-github-pr-build/1974//artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Console output:
https://builds.apache.org/job/PreCommit-ZOOKEEPER-github-pr-build/1974//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
> Assignee: Fangmin Lv
> Priority: Critical
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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