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From Thomas Becker <>
Subject Re: lucene 2.9.0RC4 slower than 2.4.1?
Date Tue, 15 Sep 2009 15:59:03 GMT

Mark Miller wrote:
> Thomas Becker wrote:
>> Hey Mark,
>> yes. I'm running the app on unix. You see the difference between 2.9 and 2.4 here:
> Right - I know your measurements showed a difference (and will keep that
> in mind) - but the profiling results then seem
> oddly similar.
Ok, got your point and agree.
>> 2.4 responds much quicker thus increasing throughput severly. I'm having a
>> single segment only:
>> -rw-r--r-- 1 asuser asgroup         20 Sep  9 16:40 segments.gen
>> -rw-r--r-- 1 asuser asgroup        294 Sep  9 16:44 segments_1o
>> -rw-r--r-- 1 asuser asgroup 2810603184 Sep  9 16:44 _7c.cfs
>> The hotspot is indeed strange. Especially if taking into
>> account that the index is lying on a tmpfs (in memory). And 2.4 should be using
>> NIOFSDirectory as well?! Will check that.
> 2.4 did not use NIOFSDirectory by default - you would have had to
> manually specified it. Now its used by default if its detects a non
> Windows OS.
Yes, I've checked that in the sources. I'm right now building the app and will
try it with SimpleFSDirectory. is replaced with new
SimpleFSDirectory. Will collect and post the results tomorrow. Seems to be a tad
faster. Details and new profiling data tomorrow. Have to leave now, sorry.
> Any particular reason your profiling output does not show invocations?
> Its not essential most likely, but I've found it to be helpful in
> comparisons.
Yes, I reduced the profiler's impact on performance. It got horribly slow with
my usual profiling settings as soon as I included the org.apache.lucene files.
> We are about to release 2.9, and its been such a long haul, I'd hate to
> see a release with an unknown performance trap.
And me too. Doing my best to find the issue. :)
Thomas Becker
Senior JEE Developer

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