[ZOOKEEPER-3127] Fixing potential data inconsistency due to update last processed zxid with partial multi-op txn

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 3.5.4, 3.6.0, 3.4.13
• Fix Version/s: 3.6.0, 3.5.5
• Component/s: server
• Labels: pull-request-available
• Assignee: Fangmin Lv
• Reporter: Fangmin Lv
• Created: 23/Aug/18 06:36
• Updated: 04/Oct/19 14:55
• Resolved: 05/Sep/18 20:36

Description

Found this issue while checking the code for another issue, this is a relatively rare case which we haven't seen it on prod so far.

Currently, the lastProcessedZxid is updated when applying the first txn of multi-op, if there is a snapshot in progress, it's possible that the zxid associated with the snapshot only include partial of the multi op.

When loading snapshot, it will only load the txns after the zxid associated with snapshot file, which could data inconsistency due to missing sub txns.

To avoid this, we only update the lastProcessedZxid when the whole multi-op txn is applied to DataTree.

Issue Links

• links to: GitHub Pull Request #606
• links to: GitHub Pull Request #631