[jira] [Commented] (FLINK-7631) Ineffective check in PageRank#open()

["Greg Hogan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-7631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16169958#comment-16169958 ] 

Greg Hogan commented on FLINK-7631:
-----------------------------------

Divide by zero is only an error for fixed-point arithmetic and here the numerator is a double.

> Ineffective check in PageRank#open()
> ------------------------------------
>
>                 Key: FLINK-7631
>                 URL: https://issues.apache.org/jira/browse/FLINK-7631
>             Project: Flink
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Priority: Minor
>
> From flink-libraries/flink-gelly/src/main/java/org/apache/flink/graph/library/linkanalysis/PageRank.java :
> {code}
>       this.vertexCount = vertexCountIterator.hasNext() ? vertexCountIterator.next().getValue() : 0;
>       this.uniformlyDistributedScore = ((1 - dampingFactor) + dampingFactor * sumOfSinks) / this.vertexCount;
> {code}
> The check for vertexCountIterator.hasNext() should enclose the assignments to both this.vertexCount and this.uniformlyDistributedScore
> Otherwise there may be divide by zero error.



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