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Adrien Grand commented on LUCENE-7258: -------------------------------------- bq. Any thoughts on this one Adrien Grand? Good question, I don't really know. :) I think Python uses 9/8 like ArrayUtil and Java uses 1.5 and I heard arguments against growth factors of 2 as they prevent freed memory from being reused since you [always need to allocate more than what has been freed so far|http://stackoverflow.com/questions/1100311/what-is-the-ideal-growth-rate-for-a-dynamically-allocated-array/1100426#1100426], but it's not clear to me how it applies to a managed runtime like Java. I think the approach from SOLR-8922 is worth trying too. > 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 > Attachments: > LUCENE-7258-Tune-memory-allocation-rate-for-Intersec.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. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org