[
https://issues.apache.org/jira/browse/ZOOKEEPER-3607?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16972124#comment-16972124
]
Jiafu Jiang commented on ZOOKEEPER-3607:
----------------------------------------
And I have fixed this problem in my personal branch, see
[https://github.com/jiafujiang/zookeeper/commit/6bd9ad1d3c0c615183d83beb80a6129365d52c42]
for my patch.
> Potential data inconsistency due to the inconsistency between
> ZKDatabase.committedLog and dataTree in Trunc sync.
> -----------------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-3607
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3607
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum
> Affects Versions: 3.4.14
> Reporter: Jiafu Jiang
> Priority: Critical
>
> I will describe the problem by a detail example.
> 1. Suppose we have three zk servers: zk1, zk2, and zk3. zk1 and zk2 are
> online, zk3 is offline, zk1 is the leader.
> 2. In TRUNC sync, zk1 sends a TRUNC request to zk2, then sends the remaining
> proposals in the committedLog. *When the follower zk2 receives the proposals,
> it applies them directly into the datatree, but not the committedLog.*
> 3. After the data sync phase, zk1 may continue to send zk2 more committed
> proposals, and they will be applied to both the datatree and the committedLog
> of zk2.
> 4. Then zk1 fails, zk3 restarts successfully, zk2 becomes the leader.
> 5. The leader zk2 sends a TRUNC request to zk3, then the remaining proposals
> from the committedLog. But since some proposals, which are from the leader
> zk1 in TRUNC sync(as I describe above), are not in the committedLog, they
> will not be sent to zk3.
> 6. Now data inconsistency happens between zk2 and zk3, since some data may
> exist in zk2's datatree, but not zk3's datatree.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
