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:

(1 comment)

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@1079
PS2, Line 1079:   BulkChangeConfigRequestPB req;
              :   auto* modify_peer = req.add_config_changes();
              :   modify_peer->set_type(MODIFY_PEER);
              :   *modify_peer->mutable_peer()->mutable_permanent_uuid() = 
move.ts_uuid_from;
              :   
modify_peer->mutable_peer()->mutable_attrs()->set_replace(false);
              :   req.set_dest_uuid(leader_uuid);
              :   req.set_tablet_id(move.tablet_uuid);
Is there a way to utilize 'cas_config_opid_index' as recorded in the 'move' 
parameter to make sure we are clearing the mark that's left from a particular 
failed move?

There might be other concurrent actors: e.g., `kudu cluster rebalance` that's 
being run by cluster operators, and the system catalog itself might 
re-replicate tablets when it finds under-replicated ones.  To avoid introducing 
disruption to the processes they run, I'd think of ways to utilize 
cas_config_opid_index here.  Otherwise, at least it's necessary to make sure we 
aren't introducing inconsistency when unconditionally clearing the flags set by 
other actors.  Most painful consequences might be situations like an 
under-replicated tablet stuck is such a state indefinitely because the 
'replace' flag was mistakenly cleared, etc.  If not utilizing the 
'cas_config_opid_index',  it's prudent to make sure we aren't ending up in 
inconsistent cluster states after mistakenly clearing the 'replace' flag that 
was set by other concurrent actors.



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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 19:38:29 +0000
Gerrit-HasComments: Yes

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