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https://issues.apache.org/jira/browse/LUCENE-888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12499548
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Michael McCandless commented on LUCENE-888:
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I re-ran the "second test" above, but this time with compound file
turned off.
Baseline (trunk) = 1 K buffers for all 3. New = 16 K for
BufferedIndexOutput, 16 K for CompoundFileWriter and 4 K for
BufferedIndexInput. I ran each test 4 times & took the best time.
Quad core Mac OS X on 4-drive RAID 0
baseline 553 sec
new 499 sec
-> 10% faster
Dual core Debian Linux (2.6.18 kernel) on 6 drive RAID 5
baseline 590 sec
new 548 sec
-> 7% faster
Windows XP Pro laptop, single drive
baseline 1078 sec
new 918 sec
-> 15% faster
Quick observations:
* Still a healthy 7-15% overall gain even without compound file by
increasing the buffer sizes.
* The overall performance gain on the trunk just by turning off
compound file ranges from 7-33% (33% gain = the Windows XP
Laptop).
OK I plan to commit this soon.
> Improve indexing performance by increasing internal buffer sizes
> ----------------------------------------------------------------
>
> Key: LUCENE-888
> URL: https://issues.apache.org/jira/browse/LUCENE-888
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Affects Versions: 2.1
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Attachments: LUCENE-888.patch, LUCENE-888.take2.patch
>
>
> In working on LUCENE-843, I noticed that two buffer sizes have a
> substantial impact on overall indexing performance.
> First is BufferedIndexOutput.BUFFER_SIZE (also used by
> BufferedIndexInput). Second is CompoundFileWriter's buffer used to
> actually build the compound file. Both are now 1 KB (1024 bytes).
> I ran the same indexing test I'm using for LUCENE-843. I'm indexing
> ~5,500 byte plain text docs derived from the Europarl corpus
> (English). I index 200,000 docs with compound file enabled and term
> vector positions & offsets stored plus stored fields. I flush
> documents at 16 MB RAM usage, and I set maxBufferedDocs carefully to
> not hit LUCENE-845. The resulting index is 1.7 GB. The index is not
> optimized in the end and I left mergeFactor @ 10.
> I ran the tests on a quad-core OS X 10 machine with 4-drive RAID 0 IO
> system.
> At 1 KB (current Lucene trunk) it takes 622 sec to build the index; if
> I increase both buffers to 8 KB it takes 554 sec to build the index,
> which is an 11% overall gain!
> I will run more tests to see if there is a natural knee in the curve
> (buffer size above which we don't really gain much more performance).
> I'm guessing we should leave BufferedIndexInput's default BUFFER_SIZE
> at 1024, at least for now. During searching there can be quite a few
> of this class instantiated, and likely a larger buffer size for the
> freq/prox streams could actually hurt search performance for those
> searches that use skipping.
> The CompoundFileWriter buffer is created only briefly, so I think we
> can use a fairly large (32 KB?) buffer there. And there should not be
> too many BufferedIndexOutputs alive at once so I think a large-ish
> buffer (16 KB?) should be OK.
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