The current head of the template repo repartitions input based on Spark's 
default parallelism, which I set on the `pio train` CLI to 4 x #-of-cores. This 
speeds up the math drastically. There are still some things that look like 
bottlenecks but taking them out make things slower. The labels you see in the 
Spark GUI should be considered approximations.

The parOpt is a mahout specific way to control partitioning and I avoid it by 
using the Spark method. 


On Nov 16, 2016, at 5:56 AM, Igor Kasianov <[email protected]> wrote:

Hi,

I'm using UR template and have some trouble with scalability.

Training take 18hours (each day) and last 12 hours it use only one core.
As I can see URAlgorithm.scala (line 144) call 
SimilarityAnalysis.cooccurrencesIDSs
with data.actions (12 partitions)

untill reduceByKey in AtB.scala it executes in parallel
but after this it executing in single thread.

It is strange, that when SimilarityAnalysis.scala(line 145) call
indexedDatasets(0).create(drm, indexedDatasets(0).columnIDs, 
indexedDatasets(i).columnIDs)
it return IndexedDataset with only one partition.

As I can see in SimilarityAnalysis.scala(line 63)
drmARaw.par(auto = true)
May be this cause decreasing the number of partitions.
As I can see in master branch of MAHOUT
has ParOpt:
https://github.com/apache/mahout/blob/master/math-scala/src/main/scala/org/apache/mahout/math/cf/SimilarityAnalysis.scala#L142
 
<https://github.com/apache/mahout/blob/master/math-scala/src/main/scala/org/apache/mahout/math/cf/SimilarityAnalysis.scala#L142>
May be this can fix the problem.

So, am I right with root of problems, and how can I fix it?


<Screenshot from 2016-11-16 15:42:36.png>
I have spark cluster with 12 Cores and 128GB but with increasing number of 
events, I can't scale UR, beause of this bottleneck

P.S., please do not suggest to use event window (I've already use it. but daily 
numer of events are increasing)

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