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From Avery Ching <ach...@apache.org>
Subject Re: Restriction of VertexInputFormat
Date Wed, 26 Oct 2011 17:26:08 GMT
Hi Gianmarco,

Welcome to Giraph!  We definitely look forward to having your 
input/contributions.  Answers inline.

On 10/26/11 8:07 AM, Gianmarco De Francisci Morales wrote:
> Hi,
>
> First of all let me introduce myself, my name is Gianmarco and I am a 
> researcher.
> Second, let me congratulate with the developers for the project. It 
> looks very promising and I am very interested in it.
>
> I have two questions.
>
> 1) I was trying to understand better the system, and I came across 
> this sentence in the documentation:
> "Currently there is one restriction on the VertexInputFormat that is 
> not obvious. The vertices must be sorted."
> Does this still apply? And if so, could someone explain me the reason?

Yes it still applies.  Please see 
https://issues.apache.org/jira/browse/GIRAPH-11.  I am getting closer to 
having this done, but got derailed by work.  Hopefully I'll have a patch 
by next week to finally address it (touches pretty much all the code).
>
> 2) Do the superstep times that get reported in hadoop counters at the 
> end of the job include communication time or only processing time?
>
It includes the time of the superstep from the master's perspective 
(waiting for workers to register health, assigning work, checkpointing 
(maybe), vertex exchange (maybe), vertex processing, waiting for all 
workers to finish, etc.).


> Thanks,
> -- 
> Gianmarco De Francisci Morales
>


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