[ https://issues.apache.org/jira/browse/ZOOKEEPER-3144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael Han resolved ZOOKEEPER-3144. ------------------------------------ Resolution: Fixed Issue resolved by pull request 621 [https://github.com/apache/zookeeper/pull/621] > Potential ephemeral nodes inconsistent due to global session inconsistent > with fuzzy snapshot > --------------------------------------------------------------------------------------------- > > Key: ZOOKEEPER-3144 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3144 > Project: ZooKeeper > Issue Type: Bug > Components: server > Affects Versions: 3.5.4, 3.6.0, 3.4.13 > Reporter: Fangmin Lv > Assignee: Fangmin Lv > Priority: Critical > Labels: pull-request-available > Fix For: 3.6.0 > > Time Spent: 20m > Remaining Estimate: 0h > > Found this issue recently when checking another prod issue, the problem is > that the current code will update lastProcessedZxid before it's actually > making change for the global sessions in the DataTree. > > In case there is a snapshot taking in progress, and there is a small time > stall between set lastProcessedZxid and update the session in DataTree due to > reasons like thread context switch or GC, etc, then it's possible the > lastProcessedZxid is actually set to the future which doesn't include the > global session change (add or remove). > > When reload this snapshot and it's txns, it will replay txns from > lastProcessedZxid + 1, so it won't create the global session anymore, which > could cause data inconsistent. > > When global sessions are inconsistent, it might have ephemeral inconsistent > as well, since the leader will delete all the ephemerals locally if there is > no global sessions associated with it, and if someone have snapshot sync with > it then that server will not have that ephemeral as well, but others will. It > will also have global session renew issue for that problematic session. > > The same issue exist for the closeSession txn, we need to move these global > session update logic before processTxn, so the lastProcessedZxid will not > miss the global session here. > > -- This message was sent by Atlassian JIRA (v7.6.3#76005)