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https://issues.apache.org/jira/browse/LUCENE-7097?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15193018#comment-15193018
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ASF subversion and git services commented on LUCENE-7097:
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Commit 8cbe4713775565a3194e29b90747f59fe2ffe3f1 in lucene-solr's branch
refs/heads/master from Mike McCandless
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=8cbe471 ]
LUCENE-7097: let IntroSorter go 2X deeper in quicksort before switching to
heapsort
> Can we increase the stack depth before Introsorter switches to heapsort?
> ------------------------------------------------------------------------
>
> Key: LUCENE-7097
> URL: https://issues.apache.org/jira/browse/LUCENE-7097
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Fix For: trunk, 6.1
>
> Attachments: LUCENE-7097.patch
>
>
> Introsort is a "safe" quicksort: it uses quicksort but detects when an
> adversary is at work and cuts over to heapsort at that point.
> The description at https://en.wikipedia.org/wiki/Introsort shows the cutover
> as 2X log_2(N) but our impl ({{IntroSorter}}) currently uses just log_2.
> So I tested using 2X log_2 instead, and I see a decent (~5.6%, from 98.2 sec
> to 92.7 sec) speedup in the time for offline sorter to sort when doing the
> force merge of 6.1 LatLonPoints from the London UK benchmark.
> Is there any reason not to switch? I know this means 2X the stack required,
> but since this is log_2 space that seems fine?
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