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https://issues.apache.org/jira/browse/CASSANDRA-7032?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14277652#comment-14277652
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Branimir Lambov commented on CASSANDRA-7032:
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No, I have not tried asymmetric configs yet, but I don't foresee significant
problems adapting the method to them. Assuming configuration is done by
specifying a number of vnodes in the node it should be just a matter of setting
the optimal size based on that number; of course it remains to be seen if that
won't cause some weird behaviour.
The speed problem is now mostly solved, I'll post a new version soon and try
that out.
> Improve vnode allocation
> ------------------------
>
> Key: CASSANDRA-7032
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7032
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Assignee: Branimir Lambov
> Labels: performance, vnodes
> Fix For: 3.0
>
> Attachments: TestVNodeAllocation.java, TestVNodeAllocation.java,
> TestVNodeAllocation.java, TestVNodeAllocation.java
>
>
> It's been known for a little while that random vnode allocation causes
> hotspots of ownership. It should be possible to improve dramatically on this
> with deterministic allocation. I have quickly thrown together a simple greedy
> algorithm that allocates vnodes efficiently, and will repair hotspots in a
> randomly allocated cluster gradually as more nodes are added, and also
> ensures that token ranges are fairly evenly spread between nodes (somewhat
> tunably so). The allocation still permits slight discrepancies in ownership,
> but it is bound by the inverse of the size of the cluster (as opposed to
> random allocation, which strangely gets worse as the cluster size increases).
> I'm sure there is a decent dynamic programming solution to this that would be
> even better.
> If on joining the ring a new node were to CAS a shared table where a
> canonical allocation of token ranges lives after running this (or a similar)
> algorithm, we could then get guaranteed bounds on the ownership distribution
> in a cluster. This will also help for CASSANDRA-6696.
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