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https://issues.apache.org/jira/browse/GIRAPH-157?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13399423#comment-13399423
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Eli Reisman commented on GIRAPH-157:
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I have asked a few people, and you're the first to answer, thanks! That makes a
lot of sense. The way I packaged it was more for testing than real use (similar
to ConnectedComponentsVertex) and I think the argument I for it in that sense
is that the code shows how, when thinking like a vertex, even hairy problems
like this are easy for dull folks like myself to reason about in a small amount
of code. As far as scaling up to where Giraph wants to be, you're exactly
right. Point taken.
My other (selfish) hope was that others such as yourself might identify if, in
fact, I oversimplified the solution to the point where it wasn't a solution at
all.
As far as time wasted, also a great point. But, my goal was to learn the
application API for Giraph (done) and get a good internship out of it (also
done.) So, if this is all it yields me and the patch withers here on the vine,
thats OK with me.
I'm more concerned about your time wasted. Sorry for that. I appreciate your
comments and spending the time to have a dialogue with me on the topic!
If I might waste a bit more of it, it seems like graph coloring can have many
applications that don't need to scale the way other Giraph algorithms will to
be somewhat useful (scheduling classes/meetings for 10k students or a
convention etc.) and while Giraph might be too much horsepower for such uses,
my thought was with Hadoop clusters cheap and everywhere now (my school has a
64 node cluster) perhaps it could take a large ugly NP problem and just lower
the runtime a bit by leveraging a cluster since the algorithm is not going to
be fast any way you stack it up. I wouldn't get this thing near a social graph.
etc.
What do you think? Is this silly? Go ahead and be honest you won't hurt my
feelings. If the algorithm is sound, the time is already wasted! Ever run
across any graphs with a known chromatic number in that size range?
Thanks again for talking to me about this, I really appreciate your input. I'll
be working on something more tangible in the coming weeks (lowering Giraph's
memory profile per worker, I hope) so perhaps I can redeem myself that way.
> Vertex to perform graph coloring on simple, connected, undirected graphs and
> related test.
> ------------------------------------------------------------------------------------------
>
> Key: GIRAPH-157
> URL: https://issues.apache.org/jira/browse/GIRAPH-157
> Project: Giraph
> Issue Type: Test
> Components: examples, test
> Affects Versions: 0.2.0
> Reporter: Eli Reisman
> Assignee: Eli Reisman
> Priority: Trivial
> Labels: newbie
> Attachments: GIRAPH-157-2.patch, GIRAPH-157.patch
>
>
> Hi. I am attempting to learn the Hadoop and Giraph codebases and wanted to
> write a simple client application for Giraph to help me learn the ins and
> outs of it. This is a simple unit test and vertex modeled after the
> ConnectedComponentsVertex and related test. The vertex test runs whenever you
> run the "mvn test" or "mvn verify" suite of tests. When finished processing,
> each vertex will have an integer value that is its color.
> This is a pretty simple implementation, and although I have tested it on a
> number of small graphs of varied trickiness and it seems to rapidly arrive at
> a minimal coloring, its hard (for me at least) to guess which possible
> coloring it will arrive at and I have no idea how it will do on really big
> graphs yet without finding some more pre-colored larger test graphs to try it
> on. Ideas anyone?
> Anyway, it was fun to put this together, and I'd be happy to improve it or
> receive some help or advice to further the cause. Thanks again, I am hoping
> this will be the first of many (hopefully more useful) contributions!
> Eli
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