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From Avery Ching <ach...@apache.org>
Subject Re: Did GIRAPH-11 break vertex reactivation?
Date Tue, 15 Nov 2011 21:03:21 GMT
Yes, I think I broke it.  Sorry.  Let me get you a diff to test quickly.

Avery

On 11/15/11 12:42 PM, Sebastian Schelter wrote:
> Hi,
>
> I updated to the latest trunk (after the GIRAPH-11 commit) and wanted to
> continue to work on GIRAPH-51 where I use a small toy graph to test
> SimpleShortestPathVertex.
>
> Unfortunately my code did not work anymore and I guess I tracked it down
> to the fact that vertex that voted to halt are not reacted anymore when
> new messages arrive.
>
> In SimpleShortestPathVertex every vertex always votes to halt and only
> gets reactivated when a shorter path to it has been found. However my
> test run always finished after superstep 0.
>
> I don't know too much about Giraph's internals yet, but my guess is that
> the number of sent messages is not tracked correctly anymore. Therefore
> giraph finishes the algorithm (as all vertices voted to halt) although
> there should still be messages in the pipeline.
>
> I think I tracked it down to this behavior:
>
> GraphMapper declares a variable workerSentMessages = 0 and never
> increases it. This variable is given to
> BspServiceWorker.finishSuperstep() which writes it to zookeeper and uses
> it to compute the GlobalStats afterwards, which are used to decide
> whether a new superstep has to be scheduled. As it has never been
> increased, the algorithm will always stop when all vertices voted to halt.
>
> It would be great if someone could confirm/disprove this speculation and
> help me to continue work on GIRAPH-51
>
> --sebastian


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