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From Doug Cutting <>
Subject Re: problems with lucene in multithreaded environment
Date Thu, 03 Jun 2004 04:32:07 GMT
Jayant Kumar wrote:
> We recently tested lucene with an index size of 2 GB
> which has about 1,500,000 documents, each document
> having about 25 fields. The frequency of search was
> about 20 queries per second. This resulted in an
> average response time of about 20 seconds approx
> per search.

That sounds slow, unless your queries are very complex.  What are your 
queries like?

> What we observed was that lucene queues
> the queries and does not release them until the
> results are found. so the queries that have come in
> later take up about 500 seconds. Please let us know
> whether there is a technique to optimize lucene in
> such circumstances. 

Multiple queries executed from different threads using a single searcher 
should not queue, but should run in parallel.  A technique to find out 
where threads are queueing is to get a thread dump and see where all of 
the threads are stuck.  In Solaris and Linux, sending the JVM a SIGQUIT 
will give a thread dump.  On Windows, use Control-Break.


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