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David Smiley updated LUCENE-7258: --------------------------------- Summary: Tune DocIdSetBuilder allocation rate (was: Tune Spatial RPT Intersects allocation rate) Wonderful graphs [~jwartes]! Any thoughts on this one [~jpountz]? I think a 2x growth rate makes more sense to me, and FWIW aligns with what java.util.ArrayList does. org.apache.lucene.util.ArrayUtil.oversize says: {code} // asymptotic exponential growth by 1/8th, favors // spending a bit more CPU to not tie up too much wasted // RAM: {code} I have had blind faith to simply use ArrayUtil.grow/oversize whenever I need to grow an array but it's shaken now. I guess it depends. If the array to be built is temporary, then don't use it -- grow by 2x; but if it may be long-lived then use it. > 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 > > 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