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Posted to dev@lucene.apache.org by "David Smiley (JIRA)" <ji...@apache.org> on 2017/03/12 04:27:04 UTC

[jira] [Closed] (LUCENE-4698) Overhaul ShapeFieldCache because its a memory pig

     [ https://issues.apache.org/jira/browse/LUCENE-4698?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David Smiley closed LUCENE-4698.
--------------------------------
    Resolution: Won't Fix

I think LatLonDocValuesField (currently in sandbox) is currently the optimal way to go about storing points per document for the purposes of distance sorting/boosting.

For general per-document access to a "shape" (possibly a MultiPoint), there's the SerializedDVStrategy.

Hence I think ShapeFieldCache stuff should be deprecated/removed.  I'll close this as won't-fix.

> Overhaul ShapeFieldCache because its a memory pig
> -------------------------------------------------
>
>                 Key: LUCENE-4698
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4698
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: modules/spatial
>            Reporter: David Smiley
>         Attachments: solr_spatial_leak1.png
>
>
> The org.apache.lucene.spatial.util.ShapeFieldCache* classes together implement a spatial field cache for points, similar to FieldCache for other fields.  It supports a variable number of points per document, and it's currently only used by the SpatialPrefixTree strategy because that's the only strategy that supports a variable number of points per document.  The other spatial strategies use the FieldCache.  The ShapeFieldCache has problems:
> * It's a memory pig. Each point is stored as a Point object, instead of an array of x & y coordinates. Furthermore, each Point is in an ArrayList that exists for each Document. It's not done any differently when your spatial data isn't multi-valued.
> * The cache is not per-segment, it's per-IndexReader, thereby making it un-friendly to NRT search.
> * The cache entries don't self-expire optimally to free up memory. The cache is simply stored in a WeakHashMap<IndexReader,ShapeFieldCache>. The big cache entries are only freed when the WeakHashMap is used and the JVM realizes the IndexSearcher instance has been GC'ed.



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