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From "Brandon Williams (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6125) Race condition in Gossip propagation
Date Thu, 18 Sep 2014 20:40:39 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14139476#comment-14139476
] 

Brandon Williams commented on CASSANDRA-6125:
---------------------------------------------

There's still a small window where a remote node could gossip with us and receive a partial
state, but that looks confined to node replacement where we'll be in a dead state and nobody
will initiate a round with us, so we just need to isolate our own propagation.

> Race condition in Gossip propagation
> ------------------------------------
>
>                 Key: CASSANDRA-6125
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6125
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Sergio Bossa
>            Assignee: Brandon Williams
>             Fix For: 2.0.11
>
>         Attachments: 6125.txt
>
>
> Gossip propagation has a race when concurrent VersionedValues are created and submitted/propagated,
causing some updates to be lost, even if happening on different ApplicationStatuses.
> That's what happens basically:
> 1) A new VersionedValue V1 is created with version X.
> 2) A new VersionedValue V2 is created with version Y = X + 1.
> 3) V2 is added to the endpoint state map and propagated.
> 4) Nodes register Y as max version seen.
> 5) At this point, V1 is added to the endpoint state map and propagated too.
> 6) V1 version is X < Y, so nodes do not ask for his value after digests.
> A possible solution would be to propagate/track per-ApplicationStatus versions, possibly
encoding them to avoid network overhead.



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