[SOLR-12176] Improve FORCELEADER to handle the case when a replica win the election but does not present in clusterstate

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 7.4
• Assignee: Cao Manh Dat
• Reporter: Cao Manh Dat
• Created: 03/Apr/18 09:14
• Updated: 08/Jun/19 15:15
• Resolved: 13/Apr/18 03:23

Description

There can be the case when a replica wins the election but it does not present in clusterstate. Maybe when the Overseer sent the UNLOAD request to the LEADER (in DeleteReplicaCmd), it met some exception (therefore the request never reach the LEADER), the Overseer it that case will forcefully remove the LEADER from clusterstate.

If a shard reaches that case, users will only see a leaderless shard and call FORCELEADER won't be able to solve their problem. Therefore FORCELEADER should be more robust, to handle such cases.