[jira] [Commented] (SPARK-8647) Potential issues with the constant hashCode

["Apache Spark (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-8647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14609580#comment-14609580 ] 

Apache Spark commented on SPARK-8647:
-------------------------------------

User 'aloknsingh' has created a pull request for this issue:
https://github.com/apache/spark/pull/7146

> Potential issues with the constant hashCode 
> --------------------------------------------
>
>                 Key: SPARK-8647
>                 URL: https://issues.apache.org/jira/browse/SPARK-8647
>             Project: Spark
>          Issue Type: Improvement
>          Components: MLlib
>    Affects Versions: 1.4.0
>            Reporter: Alok Singh
>            Priority: Minor
>              Labels: performance
>
> Hi,
> This may be potential bug or performance issue or just the code docs.
> The issue is wrt to MatrixUDT class.
>  If we decide to put instance of MatrixUDT into the hash based collection.
> The hashCode function is returning constant and even though equals method is consistant with hashCode. I don't see the reason why hashCode() = 1994 (i.e constant) has been used.
> I was expecting it to be similar to the other matrix class or the vector class .
> If there is the reason why we have this code, we should document it properly in the code so that others reading it is fine.
> regards,
> Alok
> Details
> =====
> a)
> In reference to the file 
> https://github.com/apache/spark/blob/master/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
> line 188-197 ie
>  override def equals(o: Any): Boolean = {
> o match {
> case v: MatrixUDT => true
> case _ => false
> }
> }
> override def hashCode(): Int = 1994
> b) the commit is 
> https://github.com/apache/spark/commit/11e025956be3818c00effef0d650734f8feeb436
> on March 20.



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