"The limit is that all the canopies need to fit into memory."
I don't think so. I think you can use CanopyDriver to write canopies in
a filesystem. This is done as a mapreduce job. Then the KMeansDriver
needs these canopy points as input to run KMeans.
On 20-09-2011 01:39, Jeff Eastman wrote:
Actually, most of the clustering jobs (including DirichletDriver) accept the
-Dmapred.reduce.tasks=n argument as noted below. Canopy is the only job which
forces n=1 and this is so the reducer will see all of the mapper outputs.
Generally, by adjusting T2& T1 to suitably-large values you can get canopy to
handle pretty large datasets. The limit is that all the canopies need to fit into
memory.
-----Original Message-----
From: Paritosh Ranjan [mailto:[email protected]]
Sent: Sunday, September 18, 2011 10:03 PM
To: [email protected]
Subject: Re: Clustering : Number of Reducers
So, does this mean that Mahout can not support clustering for large data?
Even in DirichletDriver the number of reducers is hardcoded to 1. And we
need canopies to run KMeansDriver.
Paritosh
On 19-09-2011 01:47, Konstantin Shmakov wrote:
For most of the tasks one can force the number of reducers with
mapred.reduce.tasks=<N>
where<N> the desired number of reducers.
It will not necessary increase the performance though - with kmeans and
fuzzykmeans combiners do reducers job and increasing the number of reducers
won't usually affect performance.
With the canopy the distributed
algorithm<http://svn.apache.org/viewvc/mahout/trunk/core/src/main/java/org/apache/mahout/clustering/canopy/CanopyDriver.java?revision=1134456&view=markup>has
no combiners and has 1 reducer hardcoded
- trying to increase #reducers won't have any effect as the algorithm
doesn't work with>1 reducer. My experience that the canopy won't scale to
large data and need improvement.
-- Konstantin
On Sun, Sep 18, 2011 at 10:50 AM, Paritosh Ranjan<[email protected]> wrote:
Hi,
I have been trying to cluster some hundreds of millions of records using
Mahout Clustering techniques.
The number of reducers is always one which I am not able to change. This is
effecting the performance. I am using Mahout 0.5
In 0.6-SNAPSHOT, I see that the MeanShiftCanopyDriver has been changed to
use any number of reducers. Will other ClusterDrivers also get changed to
use any number of reducers in 0.6?
Thanks and Regards,
Paritosh Ranjan
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