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https://issues.apache.org/jira/browse/MAHOUT-1431?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13924818#comment-13924818
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Suneel Marthi commented on MAHOUT-1431:
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yannis, could u provide explicit details as to the task name. KMeans has 2
mapper tasks and a reducer task. Which mapper is taking longer time? I would
expect ClusterClassificationMapper to be slower due to the additional overhead
of calculating the vector distance from the centroid and converting the vector
to a named vector.
> Comparison of Mahout 0.8 vs mahout 0.9 in EMR
> ---------------------------------------------
>
> Key: MAHOUT-1431
> URL: https://issues.apache.org/jira/browse/MAHOUT-1431
> Project: Mahout
> Issue Type: Question
> Components: Clustering
> Affects Versions: 0.8, 0.9
> Reporter: yannis ats
> Labels: performance
>
> Hi all,
> i tested mahout 0.8 and 0.9 in mahout emr with a large dataset as input and
> i performed kmeans experiments with both versions in amazon EMR.
> What i found is that mahout 0.8 is faster than mahout 0.9
> in particular i observed that mahout 0.8 is performing less iterations and
> every iteration of kmeans is faster than mahout 0.9.Every iteration in mahout
> 0.8 is twice as fast as that of 0.9
> the hadoop version was 1.0.x and the input of the data was roughly 2 million
> datapoints with dimensionality of 1800.
> The input parameters in both experiments were exactly the same,modulo the
> initialization which was random in both cases and i can understand that this
> may affect the convergence(the amount of iterations),but i am baffled by the
> fact that every iteration takes almost twice the time in 0.9 vs 0.8
> Is this normal?is this expected?
> thank you in advance for your time.
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