Nodes that finish the rebalance later can see outdated values ------------------------------------------------------------- Key: ISPN-5021 URL: https://issues.jboss.org/browse/ISPN-5021 Project: Infinispan Issue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 Labels: consistency, testsuite_stability Fix For: 9.1.0.Final, 9.1.0.Alpha1 Copied from [ISPN-4444|https://issues.jboss.org/browse/ISPN-4444?focusedCommentId=1302...] 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: 1. T0: read_ch=old, write_ch=old 2. start a rebalance 3. T1: read_ch=old, write_ch=old+new 4. new owners have all the data 5. T2: read_ch=new, write_ch=old+new 6. remove old cache entries and ignore further writes 7. T3: read_ch=new, write_ch=new