Alexey Serbin has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/24525 )

Change subject: KUDU-3789 auto_rebalancer: reliably clear replace marker after 
failed moves
......................................................................


Patch Set 2:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/24525/2/src/kudu/master/auto_rebalancer.cc
File src/kudu/master/auto_rebalancer.cc:

http://gerrit.cloudera.org:8080/#/c/24525/2/src/kudu/master/auto_rebalancer.cc@885
PS2, Line 885:         // Either the peer is already gone from the config 
(NotFound), or the
             :         // marker is already cleared so the no-op MODIFY_PEER 
was rejected
             :         // (InvalidArgument). Both mean there's nothing left to 
do.
             :         if (clear_replace_status.IsNotFound() ||
             :             clear_replace_status.IsInvalidArgument()) {
             :           clear_replace_status = Status::OK();
             :           break;
             :         }
IIUC, AutoRebalancerTask::GetTabletLeader() (which is a part of 
AutoRebalancerTask::TryClearReplaceMarker()) can intermittently return 
Status::NotFound() when no replica is a leader: that can happen during election 
rounds, etc.

Are we OK with bailing out and not removing the marker in such a case?


http://gerrit.cloudera.org:8080/#/c/24525/2/src/kudu/master/auto_rebalancer.cc@1102
PS2, Line 1102:   // Without catalog leadership we can't resolve tablet 
leaders, and any
              :   // marker we left behind is now the new leader's 
responsibility.
              :   {
              :     CatalogManager::ScopedLeaderSharedLock l(catalog_manager_);
Once exited from this scope, how do we know that we are still the leader to 
call TryClearReplaceMarker() below?  What if the leadership changes right after 
releasing this lock -- does the code below behaves as expected?



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ia47698207612252bca3ec70fc090a37bd3f87809
Gerrit-Change-Number: 24525
Gerrit-PatchSet: 2
Gerrit-Owner: Gabriella Lotz <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Gabriella Lotz <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Marton Greber <[email protected]>
Gerrit-Reviewer: Zoltan Martonka <[email protected]>
Gerrit-Comment-Date: Fri, 10 Jul 2026 18:49:53 +0000
Gerrit-HasComments: Yes

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