Hello,

Something on http://lucene.apache.org/mahout/taste.html#performance caught my 
attention:

-XX:+NewRatio=9: Increase heap allocated to 'old' objects, which is most of 
them in this framework

So I looked up this java parameter on 
http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp :


-XX:NewRatio=2
Ratio of new/old generation sizes. [Sparc -client: 8; x86 -server: 8; x86 
-client: 12.]-client: 4 (1.3) 8 (1.3.1+), x86: 12]

If I'm reading this correctly, the larger the number, the bigger portion of the 
heap is used for "old" objects.
Also, it looks like different platforms have different defaults, so maybe 
advising a single "9" value is not the right thing to do?
For example, it looks like on x86 the default is 12, so using NewRatio=9 would 
actually decrease the space for old objects.

I'd love to hear from anyone who actually knows what this means, how it should 
be used, and if anyone has actually used different values with a large Taste 
instance.

Thanks,
Otis
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