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From Eli Reisman <>
Subject Re: InputFormat for the example SimpleMasterComputeVertex
Date Thu, 21 Feb 2013 18:25:15 GMT
Thanks for the explanation, that makes sense. I would love to see a wiki
page at some point, you have so much knowledge of this piece of Giraph from
all your dev work on it and have also the additional bonus of experience
running big cluster jobs using these features so you have a lot of insight
to share.

Would there be any point to a future JIRA to break out the aggregator
registration from the master compute stuff, at least from the user's view?
Or is it not that confusing once you've used them a bit?

On Thu, Feb 14, 2013 at 4:52 PM, Maja Kabiljo <> wrote:

>  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 <>wrote:
>> Hey,
>>  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*(*42*)
>> 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,
>> Thanks!
>>  Maria
>> --
>> 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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