[ZOOKEEPER-2513] majorChange exceptions during leader sync

• Type: Bug
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: 3.5.2
• Component/s: server
• Assignee: Mohammad Arshad
• Reporter: Alexander Shraer
• Created: 14/Aug/16 00:46
• Updated: 05/Sep/16 23:02

Description

In Learner.java there are exceptions being thrown in case majorChange = true, i.e., a reconfig is encountered in the stream of updates from the leader. There may be two problems in the way such exceptions are thrown:
1. important actions, e.g., processTxn, will not be done if an exception is thrown
2. its unclear that the learner will be able to continue where it left off in the process of syncing with the leader, if that sync is interrupted by an exception.

This requires further investigation. Whereas similar code in Follower and Observer is extensively tested, this code in Learner isn't tested as much. We could build on the test case developed in ZOOKEEPER-2172 to make sure this code works properly.

Issue Links

• depends upon: ZOOKEEPER-2172 Cluster crashes when reconfig a new node as a participant