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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3442) QuickSort may get into unbounded recursion
Date Wed, 28 May 2008 22:22:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12600629#action_12600629
] 

Chris Douglas commented on HADOOP-3442:
---------------------------------------

It's not sorted data (which should produce relatively even partitions per lines 58-60), but
horribly unlucky pivot selections that could produce this. Since the JVM doesn't appear to
recognize the tail recursion, it's possible that a series- meaning hundreds- of sequential
median values sampled from the left, right, and midpoint could be so skewed that the recursion
could top out (a bad comparator might hurt pivot selection). This should be _fantastically_
unlikely, though. Does this happen with HADOOP-3308 applied?

> QuickSort may get into unbounded recursion
> ------------------------------------------
>
>                 Key: HADOOP-3442
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3442
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.17.0
>            Reporter: Runping Qi
>


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