[infinispan-issues] [JBoss JIRA] (ISPN-5021) Nodes that finish the rebalance later can see outdated values

[Dan Berindei (JIRA)]

Dan Berindei created ISPN-5021:
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             Summary: Nodes that finish the rebalance later can see outdated values
                 Key: ISPN-5021
                 URL: https://issues.jboss.org/browse/ISPN-5021
             Project: Infinispan
          Issue Type: Bug
          Components: Core, State Transfer
    Affects Versions: 7.0.2.Final
            Reporter: Dan Berindei
            Assignee: Pedro Ruivo
            Priority: Critical
             Fix For: 7.1.0.Alpha1


Copied from [ISPN-4444|https://issues.jboss.org/browse/ISPN-4444?focusedCommentId=13022645#comment-13022645]

If the CH_UPDATE command is delayed on the old owner, the new owners might update the key without the old owner knowing, and a locality check on the old owner won't help.

I remember one thing that struck me when reading the Raft algorithm was that they install configuration changes symmetrically, in 3 phases. We might need to do the same for our rebalance: start a rebalance with read_ch=old, write_ch=old+new, when the new owners have all the data install read_ch=new, write_ch=old+new, and finally read_ch=new, write_ch=new. Old cache entries are removed during the 2nd topology update, and further writes should be ignored, in order for this to work.




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