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From: Alessandro Presta <alessandro@fb.com>
To: "dev@giraph.apache.org" <dev@giraph.apache.org>
Subject: Re: [jira] [Commented] (GIRAPH-191) Random Walks on Graphs
Thread-Topic: [jira] [Commented] (GIRAPH-191) Random Walks on Graphs
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Date: Sat, 11 Aug 2012 18:59:35 +0000
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Hi Gianmarco,

I sympathize with that. However, I can't think of a way to avoid it:
Vertex needs to be defined in terms of Writables, we depend on that for
serialization (which enables communication and fault tolerance).
Was it any different in the 0.1 API? The only thing I can think of is that
now a vertex with weighted edges needs to return Edge objects in its
iterator.

That said, if you're writing your own vertex with optimized edge storage,
I guess you could add iterators over primitive types, and use those in
your algorithm. However, for example, you would still have to wrap values
in Writables for message passing.
But yeah, if this is for a vertex that gets shipped with Giraph, we
probably don't want to do that.

Please let me know if I understood the issue and any ideas you might have
to improve it.

Alessandro

On 8/10/12 6:37 PM, "Gianmarco De Francisci Morales" <gdfm@apache.org>
wrote:

>Hi Alessandro,
>
>My main concern is that I need a lot of wrapping objects if I want to keep
>data as primitive values in the vertex implementation.
>Right now I have some wrapper iterables/iterators that do that, but I
>think
>all this temporary object creation kind of kills the memory efficiency of
>the vertex implementation.
>
>I am rebasing the patch once again after the aggregator changes (and
>trying
>to understand how they work now).
>As soon as I finish and Jira comes up again I will post an updated patch.
>
>Cheers,
>--
>Gianmarco
>
>
>
>On Thu, Aug 9, 2012 at 4:00 PM, Alessandro Presta (JIRA)
><jira@apache.org>wrote:
>
>>
>>     [
>>=20
>>https://issues.apache.org/jira/browse/GIRAPH-191?page=3Dcom.atlassian.jir=
a.
>>plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D13431815=
#c
>>omment-13431815]
>>
>> Alessandro Presta commented on GIRAPH-191:
>> ------------------------------------------
>>
>> Gianmarco: can you elaborate more on the difficulties you're having with
>> vertex implementation?
>>
>> > Random Walks on Graphs
>> > ----------------------
>> >
>> >                 Key: GIRAPH-191
>> >                 URL: https://issues.apache.org/jira/browse/GIRAPH-191
>> >             Project: Giraph
>> >          Issue Type: New Feature
>> >          Components: examples
>> >    Affects Versions: 0.2.0
>> >            Reporter: Gianmarco De Francisci Morales
>> >            Assignee: Gianmarco De Francisci Morales
>> >         Attachments: GIRAPH-191-1.patch, GIRAPH-191.2.patch,
>> GIRAPH-191.patch, PIG-191.1.patch
>> >
>> >
>> > Implementing RWR on Giraph should be a very simple modification of the
>> SimplePageRankVertex code.
>> > {code}
>> > if ( myID =3D=3D sourceID )
>> >       DoubleWritable vertexValue =3D new DoubleWritable((0.15f + 0.85f=
 *
>> sum);
>> > else
>> >       DoubleWritable vertexValue =3D new DoubleWritable(0.85f * sum);
>> > {code}
>> > It would be nice to make it as configurable as possible by using
>> parametric damping factors, preference vectors, strongly preferential,
>> etc...
>> > More or less along these lines:
>> >
>>=20
>>http://law.dsi.unimi.it/software/docs/it/unimi/dsi/law/rank/PageRank.html
>>
>> --
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>>
>>