[infinispan-issues] [JBoss JIRA] Commented: (ISPN-1275) Virtual nodes producing same hash id for two different cluster nodes

[Galder Zamarreño (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-1275?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12617488#comment-12617488 ] 

Galder Zamarreño commented on ISPN-1275:
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I'm leaning towards the Hot Rod server re-calculating the hash ids for all nodes in the topology on startup, and to make this as efficient as possible, add a getHashIds(List<Address> addresses) to AbstractWheelConsistentHash. That way, we'd avoid looping through all positionValues for each address. Passing a list of addresses, we do it once and we've done it for all nodes in the cluster. I think it'd the lesser of evils.

> Virtual nodes producing same hash id for two different cluster nodes
> --------------------------------------------------------------------
>
>                 Key: ISPN-1275
>                 URL: https://issues.jboss.org/browse/ISPN-1275
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Distributed Cache
>    Affects Versions: 5.0.0.CR8
>            Reporter: Galder Zamarreño
>            Assignee: Manik Surtani
>            Priority: Blocker
>             Fix For: 5.0.0.FINAL
>
>         Attachments: hashids.log
>
>
> While working on ISPN-1273, I've discovered that when virtual nodes are enabled, ConsistentHash.getHashIds(address) can return the same hash for two different cluster nodes. Example: with 500 virtual nodes, both NodeA-23181 and NodeB-39177 produce hash id *5289*. See attached log.

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