[infinispan-dev] MurmurHash fixes

[Emmanuel Bernard]

Or release a 4.3.

On 14 janv. 2011, at 09:32, Bela Ban wrote:

> I would fix the existing MurmurHash; IMO backward compat doesn't extend 
> to consistent hashing...
> 
> Does leaving the 1 bit out create extreme anomalies wrt hashing 
> distribution ? I wouldn't think so...
> 
> I'm fine with the other solution, too.
> 
> 
> 
> On 1/13/11 8:35 PM, Manik Surtani wrote:
>> Guys,
>> 
>> The MurmurHash2 impl we have in 4.2.0 is buggy in that my translation from the original C source was faulty and it effectively hashes over just 31 bits instead of 32.  It means the distribution result isn't as good as it could be.
>> 
>> Now it isn't that easy for me to just *fix* this in 4.2.1, since it means keys mapped to nodes using 4.2.0 may not map to the same node in 4.2.1.
>> 
>> So here is what I propose:
>> 
>> 1) Fix it in 4.2.x as MurmurHash2A
>> 2) Use MurmurHash2A by default, *unless* a config flag is provided that forces the use of MurmurHash2.  (e.g.,<hash function="MurmurHash2">)
>> 
>> This will even give us the ability to use MurmurHash3 in 5.0 when we have it.
>> 
>> WDYT?
> 
> 
> -- 
> Bela Ban
> Lead JGroups / Clustering Team
> JBoss
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