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From "Matthieu Morel (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (S4-30) DefaultHasher hashes keys to negative number
Date Tue, 20 Dec 2011 12:53:30 GMT

    [ https://issues.apache.org/jira/browse/S4-30?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13173159#comment-13173159
] 

Matthieu Morel commented on S4-30:
----------------------------------

Thanks for reporting this. 

Unfortunately, I was not able to reproduce the problem. Do you have a test case?

I'm a bit surprised because the adapted version of the algorithm we use strips 64 bits values
to unsigned 32 bits integers. (see: https://github.com/s4/s4/blob/master/s4-core/src/main/java/org/apache/s4/dispatcher/partitioner/HashAlgorithm.java#L145)

                
> DefaultHasher hashes keys to negative number
> --------------------------------------------
>
>                 Key: S4-30
>                 URL: https://issues.apache.org/jira/browse/S4-30
>             Project: Apache S4
>          Issue Type: Bug
>    Affects Versions: 0.4
>         Environment: All - Windows and Linux
>            Reporter: Quoc Nguyen
>            Priority: Blocker
>
> DefaultHasher uses HashAlgorithm hashAlgorithm = HashAlgorithm.FNV1_64_HASH; which hashes
key strings such as 118+18233, 118+17360, 118+17258, 118+18147 and 118+18121 and many more
to negative values which the DefaultPartitioner (int partitionId = (int) (hasher.hash(stringValue)
% partitionCount);) tries to partition the key to incorrect partition.
> Workaround:
> None - stream has those keys, they will get dropped because the partitioner cannot correctly
partition.

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