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From Marcel Reutegger <marcel.reuteg...@gmx.net>
Subject Re: Threading and Query Performance
Date Wed, 14 Mar 2007 13:34:38 GMT
Tobias Bocanegra wrote:
> well, from a first glance: the more threads you add, the faster the
> queries are until you reach the number of processors. if you expect
> linear improvement - that does not work, since the actual 'searching'
> is synchronized (marcel, correct me if i'm saying something wrong
> here).

it's not fully synchronized, queries do run in parallel, which can be seen in 
Davids results. but at a lower level, probably in lucene, some part of the query 
execution is synchronized.

An easy way to find out what parts of the query execution is synchronized, is to 
get a thread dump while the queries are running. This will show you/us where the 
threads are waiting during their execution. To simplify analysis I'd recommend 
to run only a couple of queries concurrently, e.g. equal to the number of 
processors you have.


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