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From Yonik Seeley <>
Subject Re: Throughput doesn't increase when using more concurrent threads
Date Mon, 21 Nov 2005 15:43:30 GMT
This is expected behavior: you are probably quickly becoming CPU bound
(which isn't a bad thing).  More threads only help when  some threads
are waiting on IO, or if you actually have a lot of CPUs in the box.

Now hiring --

On 11/21/05, Oren Shir <> wrote:
> Hi,
> I tried stressing Lucene in a controlled environment: one static
> IndexSearcher for an index that doesn't change, and in same process I create
> a number of Threads that call this Searcher concurrently for a limited time.
> I expected the number of successful queries to increase when using more
> threads, but this is not the case. From 1 thread to 10 I see 25% increase,
> but from 10 threads to 100 there is no change, only the average response
> time increases. same goes for 200 threads. I tried RAMDirectory and
> FSDirectory, and the behavior is the same.
> I Extract the first 100 results from the Hits object, but on RAMDirectory
> this should be insignificant, right?
> I tested this in version 1.4.3 and 1.9rc1, and they are both the same in
> this aspect. 1.9rc1 is faster, but does not benefit from multi threading.
> Did anyone see other behaviour?
> Will it be better to dedicate a searcher for each thread (maybe
> Thanks,
> Oren Shir

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