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From Maja Kabiljo <>
Subject Re: InputFormat for the example SimpleMasterComputeVertex
Date Fri, 15 Feb 2013 00:52:28 GMT
Progressable exception can be caused by many different reasons (it's totally unrelated to aggregators),
and when looking at which exception it's caused by users should get better sense about what's
going on.
What you are suggesting about providing default master compute is not doable, since the part
which needs to be done there is aggregator registration. We can't know what kind of aggregators
(names and types) an application needs.
I remember I was talking about writing a short tutorial for aggregators long time ago, sorry
for not doing that, will try to get to it soon.

From: Eli Reisman <<>>
Reply-To: "<>" <<>>
Date: Thursday, February 14, 2013 2:23 PM
To: "<>" <<>>
Subject: Re: InputFormat for the example SimpleMasterComputeVertex

Other folks on the list are also having this problem with the progressable utile exception
& job failures. I don't know much about master compute usage but if it is needed to make
the aggregators work, maybe we should have a default dummy class that just handles aggregators
if no other master compute is specified? Or a wiki page? The progressable error message does
not lead us to this conclusion directly.

On Wed, Feb 13, 2013 at 3:04 AM, Maria Stylianou <<>>

I am trying to run the example SimpleMasterComputeVertex, but no matter which Input Format
and graph I give, it doesn't work. Each worker gives the error:

Caused by: java.lang.NullPointerException
        at org.apache.giraph.examples.SimpleMasterComputeVertex.compute(

This line 42 is the first line of the compute()
public void compute(Iterable<DoubleWritable> messages){

So I guess, the initialization is not done correctly, because the input file does not have
the correct format.

Any help would be appreciated,
Maria Stylianou
Intern at Telefonica, Barcelona, Spain
Master Student of European Master in Distributed Computing<>
Universitat Polit├Ęcnica de Catalunya - BarcelonaTech, Barcelona, Spain
KTH Royal Institute of Technology, Stockholm, Sweden

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