[
https://issues.apache.org/jira/browse/LUCENE-7258?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
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: [email protected]
For additional commands, e-mail: [email protected]
