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From Ameya Vilankar <>
Subject Re: Waking up all the vertices after every vertex calls vote to halt
Date Thu, 21 Nov 2013 22:57:18 GMT
I have implemented Alternating Least Squares on top apache giraph. On the
edge, I store the type of the edge. Edges can be either a training edge or
testing edge. When I run the algorithm, I use only the ratings on the
training edge to tune the vectors on the vertices.
The algorithm ends in one of the two scenarios:
1. All the vertices have tuned their vector with in the tolerable error. At
this point there are no active vertices since everyone has called vote to
2. We reached the maximum number of supersteps. At this point, some
vertices are active since they received messages from the last superstep.

I have written an Aggregator that counts the training error along this
process. But now, I want to calculate the prediction/testing error which is
along the testing labelled edges. But there are either no active vertices
or few active vertices at this point in my algorithm. I need all the
vertices to send their vectors along all of their testing edges to compute
the testing error and send it to a error sum aggregator. For this I need to
activate all the vertices.
Hope it is clear to you now.


On Thu, Nov 21, 2013 at 2:45 PM, Claudio Martella <> wrote:

> Hi Ameya,
> I'm not sure I understand the problem correctly. The maximum number of
> supersteps allows you to halt the computation when that threshold is
> reached. The RMSE can be computed within the master compute.
> What do you want to achieve exactly?
> On Thu, Nov 21, 2013 at 10:47 PM, Ameya Vilankar <
> > wrote:
>> Hi,
>> I am implementing a machine learning algorithm on top giraph. The
>> algorithm converges when all the vertices call voteToHalt or some max
>> number of supersteps have completed.
>> I want to calculate the RMSE error  after the algorithm has converged.
>> But the problem is either all the vertices have called vote to halt or (in
>> the case where we reach max supersteps) only some of them are still active.
>> I need to reactivate or wake up all the vertices. Is there any way in
>> giraph that I could do this?
>> Thanks,
>> Ameya Vilankar
>> Zynga
> --
>    Claudio Martella

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