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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3442) QuickSort may get into unbounded recursion
Date Mon, 09 Jun 2008 21:24:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12603694#action_12603694
] 

Tsz Wo (Nicholas), SZE commented on HADOOP-3442:
------------------------------------------------

- QuickSort.getMaxDepth can be more aggressive: since the index are int, we have n <= 2^32
and lg n <= 32.  So, we could safely let QuickSort.getMaxDepth be something around (lg
n)^3 or it should depend on the maximum size of system stack.

- HeapSort is a singleton.  Define a static variable HeapSort.INSTANCE.  Then, we don't have
to new HeapSort() in QuickSort.

- public methods HeapSort.sort(IndexedSortable s, int p, int r) and QuickSort.sort(...) need
javadoc.

- There are quite a few sorting classes/interfaces.  Consider create a new package for them.

- Remove BatcherSort in this patch.  Create a new issue if it is useful.


> 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
>            Assignee: Chris Douglas
>            Priority: Blocker
>             Fix For: 0.17.1, 0.18.0
>
>         Attachments: 3442-0.patch, 3442-0v17.patch, 3442-1.patch, 3442-2.patch, CheckSortBuffer.java,
HADOOP-3442.patch, overflow.zip, spillbuffers.patch
>
>


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