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Posted to dev@mahout.apache.org by "Robin Anil (Commented) (JIRA)" <ji...@apache.org> on 2012/01/14 22:22:39 UTC
[jira] [Commented] (MAHOUT-890) Performance issue in FPGrowth
[ https://issues.apache.org/jira/browse/MAHOUT-890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13186345#comment-13186345 ]
Robin Anil commented on MAHOUT-890:
-----------------------------------
The Patch fails when applying. Can you send me a new one
> Performance issue in FPGrowth
> -----------------------------
>
> Key: MAHOUT-890
> URL: https://issues.apache.org/jira/browse/MAHOUT-890
> Project: Mahout
> Issue Type: Bug
> Components: Frequent Itemset/Association Rule Mining
> Affects Versions: 0.6
> Reporter: tom pierce
> Attachments: MAHOUT-890-2.patch, MAHOUT-890-3.patch, MAHOUT-890.patch, addSynth.patch, logtrees.patch, simpleFPG.patch, smallexample.dat
>
>
> I've encountered a dataset which indicates there is probably a performance bug lurking in the FPGrowth implementation. This set may be a bit of an unusual target for FPG - there's a relatively modest number itemsets, and many items with a Zipfy distribution. I am attaching a patch (addSynth.patch) to add a similar dataset as core/src/test/resources/FPGsynth.dat.
> FPGsynth.dat can take minutes or a few hours to process, depending on how it is grouped out to machines. If run in sequential mode, or with "-g 50" it will take considerable time. Most reducers/"anchor items" are processed quickly, but a small number take a handful of minutes, and one or two take a long time. If you experiment with this data, I suggest using '-s 50 -regex "[ ]+"'.
> Digging into this, I've found that the tree pruning code sometimes creates surprising trees. One oddity I've observed is 0-count nodes, sometimes with non-zero children. The other is that sometimes subtrees seem to get repeated. I'm attaching a sample input file (smallexample.dat, use the whitespace regex with this one, too) and a patch which adds some logging in pruneFPTree and growthBottomUp which will print out some interesting trees when run with the smallexample.dat input.
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