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From Timo Nentwig <luc...@nitwit.de>
Subject Re: CachingWrapperFilter: why cache per IndexReader?
Date Tue, 01 Jan 2008 19:40:35 GMT
On Tuesday 01 January 2008 19:26:51 Grant Ingersoll wrote:
> My guess would be b/c best practice is usually to only have one Reader/
> Searcher per Directory, but I don't know if that is the real reason.
> Most discussions/testing I have seen indicate a single Reader/Searcher
> performs best.

Well, I read this (in the FAQ) that I should use only a single 
Searcher/Reader. And I really would like to but I ran into some FSDirectory 
IO synchronized{} bottleneck and hence (still) don't see any alternative to 
pooling multiple seachers (which waste a lot of memory).

Even LUCENE-997 doesn't produce relief here... :-\

But in general, since IndexSearcher is single-threaded I don't think that this 
a wise approach. No matter how large the index, no matter the IO system, no 
matter how many queries you want all this to go thru a single thread? How 
long since does a single thread plus synchronous IO scale?

However I yet didn't find any discussion on this topic so I'd be glad if 
somebody could give me a link.

> -Grant
>
> On Jan 1, 2008, at 11:57 AM, Timo Nentwig wrote:
> > Hi!
> >
> > Is there are particular reason why CachingWrapperFilter caches per
> > IndexReader
> > and not per IndexReader.directory()? If there are multiple
> > IndexSearcher/IndexReader instances (and only one Directory) cache
> > will be
> > built and held in memory redundantly. I don't see any sense in doing
> > so (?).
> >
> > Thanks for hints...
> > Timo
> >
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> --------------------------
> Grant Ingersoll
> http://lucene.grantingersoll.com
> http://www.lucenebootcamp.com
>
> Lucene Helpful Hints:
> http://wiki.apache.org/lucene-java/BasicsOfPerformance
> http://wiki.apache.org/lucene-java/LuceneFAQ
>
>
>
>
>
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