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From "Aviran" <>
Subject RE: FW: Lucene Search has poor cpu utilization on a 4-CPU machine
Date Thu, 15 Jul 2004 13:34:55 GMT

> The second one is on
> org.apache.lucene.index.SegmentReader.norms( 
> which is a synchronized method thus causing locks. I guess the 
> synchronization is done for a good reason, but you probably know the 
> answer better then me.

I'm surprised this is showing up.  Can you tell more about the size of 
your index and the nature of your queries?  If you're, e.g., doing lots 
of range or wildcard queries, then I can maybe see this showing up a 
little.  What is your benchmark like?

Are you "warming the cache" when you're performing these benchmarks?  In 
other words, are you first sending a few queries at a low rate before 
you start slamming it with high traffic?  If you're not, and/or you have 
a lot of fields, or you re-open searchers a lot, then this could show up 


My test index is pretty small size, about 250 documents and about 24 fields
in each document. 
The test is done by starting 10 threads that repeat simple one word query
(each thread query on a different word). Neither range nor wildcard query is
I let the test run for about a minute and then I do a full thread dump to
see the stack trace.
I use a single searcher which never gets closed.


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