Andrew Ray created SPARK-18845:
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Summary: PageRank has incorrect initialization value that leads to
slow convergence
Key: SPARK-18845
URL: https://issues.apache.org/jira/browse/SPARK-18845
Project: Spark
Issue Type: Bug
Components: GraphX
Affects Versions: 2.0.2, 1.6.3, 1.5.2, 1.4.1, 1.3.1, 1.2.2
Reporter: Andrew Ray
All variants of PageRank in GraphX have incorrect initialization value that
leads to slow convergence. In the current implementations ranks are seeded with
the reset probability when it should be 1. This appears to have been introduced
a long time ago in
https://github.com/apache/spark/commit/15a564598fe63003652b1e24527c432080b5976c#diff-b2bf3f97dcd2f19d61c921836159cda9L90
This also hides the fact that source vertices (vertices with no incoming edges)
are not updated. This is because source vertices generally* have pagerank equal
to the reset probability. Therefore both need to be fixed at once.
PR will be added shortly
*when there are no sinks -- but that's a separate bug
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