[infinispan-issues] [JBoss JIRA] (ISPN-5533) M/R DeltaAwareList can add duplicate values because of topology changes

[Dan Berindei (JIRA)]

Dan Berindei created ISPN-5533:
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             Summary: M/R DeltaAwareList can add duplicate values because of topology changes
                 Key: ISPN-5533
                 URL: https://issues.jboss.org/browse/ISPN-5533
             Project: Infinispan
          Issue Type: Bug
          Components: Core, Distributed Execution and Map/Reduce
    Affects Versions: 8.0.0.Alpha1, 7.2.2.Final
            Reporter: Dan Berindei
             Fix For: 8.0.0.Final


By default, the intermediate cache is non-transactional, so a topology change will cause write commands to be retried. Because a {{PutKeyValueCommand(K, DeltaAwareList)}} command is not idempotent, a retried command will append extra intermediate values to the list.

The M/R framework tries to guard against this by waiting for all the nodes to initialize the intermediate cache before starting the reduce phase, but it cannot guard against nodes joining or leaving during the reduce phase.



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