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https://issues.apache.org/jira/browse/CASSANDRA-16286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17269765#comment-17269765
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Caleb Rackliffe commented on CASSANDRA-16286:
---------------------------------------------

[~cscotta] I know this has been a potential problem for years (and certainly 
before 4.0), but I'd like to try to throw a patch together first to see if it's 
as simple as I think it is. If I don't get around to it by the end of the 
month, I won't argue against pushing it to an early 4.0.x release.

> Make TokenMetadata's ring version increments atomic
> ---------------------------------------------------
>
>                 Key: CASSANDRA-16286
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-16286
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Cluster/Gossip
>            Reporter: Caleb Rackliffe
>            Assignee: Caleb Rackliffe
>            Priority: Normal
>             Fix For: 3.0.x, 3.11.x, 4.0-rc
>
>
> The update semantics of the ring version in {{TokenMetadata}} are not clear. 
> The instance variable itself is {{volatile}}, but it is still incremented by 
> a non-atomic check-and-set, and not all codepaths do that while holding the 
> {{TokenMetadata}} write lock. We could make this more intelligible by forcing 
> the external callers to use both the write when invalidating the ring and 
> read lock when reading the current ring version. Most of the readers of the 
> ring version (ex. compaction) don't need it to be fast, but it shouldn't be a 
> problem even if they do. If we do this, we should be able to avoid a 
> situation where concurrent invalidations don't produce two distinct version 
> increments.



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