[jira] [Assigned] (KUDU-3098) leadership change during tablet_copy process may lead to an isolate replica

["Alexey Serbin (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KUDU-3098?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alexey Serbin reassigned KUDU-3098:
-----------------------------------

    Assignee:     (was: Alexey Serbin)

> leadership change during tablet_copy process may lead to an isolate replica
> ---------------------------------------------------------------------------
>
>                 Key: KUDU-3098
>                 URL: https://issues.apache.org/jira/browse/KUDU-3098
>             Project: Kudu
>          Issue Type: Bug
>          Components: consensus, master
>    Affects Versions: 1.10.1
>            Reporter: YifanZhang
>            Priority: Major
>
> Lately we found some tablets in a cluster with a very large "time_since_last_leader_heartbeat" metric, they are LEARNER/NON_VOTER and seems couldn't become VOTER for a long time.
> These replicas created during the rebalance/tablet_copy process. After beginning a new copy session from leader to the new added NON_VOTER peer, leadership changed, old leader aborted uncommited CHANGE_CONFIG_OP operation. Finally the tablet_copy session ended but new leader knew nothing about the new peer. 
> Master didn't delete this new added replica because it has a larger opid_index than the latest reported committed config. See the comments in CatalogManager::ProcessTabletReport
> {code:java}
> // 5. Tombstone a replica that is no longer part of the Raft config (and
> // not already tombstoned or deleted outright).
> //
> // If the report includes a committed raft config, we only tombstone if
> // the opid_index is strictly less than the latest reported committed
> // config. This prevents us from spuriously deleting replicas that have
> // just been added to the committed config and are in the process of copying.
> {code}
> Maybe we shouldn't use opid_index to determine if replicas are in the process of copying.



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