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From Sebastian Schelter <>
Subject Did GIRAPH-11 break vertex reactivation?
Date Tue, 15 Nov 2011 20:42:28 GMT

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

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


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