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Posted to dev@lucene.apache.org by "Adrien Grand (JIRA)" <ji...@apache.org> on 2016/05/23 07:29:13 UTC
[jira] [Resolved] (LUCENE-7258) Tune DocIdSetBuilder allocation
rate
[ https://issues.apache.org/jira/browse/LUCENE-7258?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Adrien Grand resolved LUCENE-7258.
----------------------------------
Resolution: Fixed
Fix Version/s: master (7.0)
6.1
> Tune DocIdSetBuilder allocation rate
> ------------------------------------
>
> Key: LUCENE-7258
> URL: https://issues.apache.org/jira/browse/LUCENE-7258
> Project: Lucene - Core
> Issue Type: Improvement
> Components: modules/spatial
> Reporter: Jeff Wartes
> Fix For: 6.1, master (7.0)
>
> Attachments: LUCENE-7258-Tune-memory-allocation-rate-for-Intersec.patch, LUCENE-7258-Tune-memory-allocation-rate-for-Intersec.patch, LUCENE-7258-expanding.patch, LUCENE-7258.patch, allocation_plot.jpg
>
>
> LUCENE-7211 converted IntersectsPrefixTreeQuery to use DocIdSetBuilder, but didn't actually reduce garbage generation for my Solr index.
> Since something like 40% of my garbage (by space) is now attributed to DocIdSetBuilder.growBuffer, I charted a few different allocation strategies to see if I could tune things more.
> See here: http://i.imgur.com/7sXLAYv.jpg
> The jump-then-flatline at the right would be where DocIdSetBuilder gives up and allocates a FixedBitSet for a 100M-doc index. (The 1M-doc index curve/cutoff looked similar)
> Perhaps unsurprisingly, the 1/8th growth factor in ArrayUtil.oversize is terrible from an allocation standpoint if you're doing a lot of expansions, and is especially terrible when used to build a short-lived data structure like this one.
> By the time it goes with the FBS, it's allocated around twice as much memory for the buffer as it would have needed for just the FBS.
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