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https://issues.apache.org/jira/browse/JENA-2311?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andy Seaborne resolved JENA-2311.
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Fix Version/s: Jena 4.6.0
Assignee: Andy Seaborne
Resolution: Done
> query rewrite index does too expensive caching on geo literals
> --------------------------------------------------------------
>
> Key: JENA-2311
> URL: https://issues.apache.org/jira/browse/JENA-2311
> Project: Apache Jena
> Issue Type: Improvement
> Components: GeoSPARQL
> Affects Versions: Jena 4.4.0
> Reporter: Lorenz Bühmann
> Assignee: Andy Seaborne
> Priority: Major
> Fix For: Jena 4.6.0
>
>
> Using a GeoSPARQL query with a geospatial property function, e.g.
> {code:java}
> SELECT * {
> :x geo:hasGeometry ?geo1 .
> ?s2 geo:hasGeometry ?geo2 .
> ?geo1 geo:sfContains ?geo2
> }
> {code}
> leads to heavy memory consumption for larger datasets - and we're not talking
> about big data at all. Imagine given a polygon and checking for millions of
> geometries for containment in the polygon.
> In the {{QueryRewriteIndex}} class for caching a key will be generated, but
> this is horribly expensive given that the string representation of Geometries
> is called millions of times leading millions of Byte arrays being created
> leading a to a possible OOM exception - we got it with 8GB assigned.
> The key generation for reference:
> {code:java}
> String key = subjectGeometryLiteral.getLiteralLexicalForm() + KEY_SEPARATOR +
> predicate.getURI() + KEY_SEPARATOR +
> objectGeometryLiteral.getLiteralLexicalForm();
> {code}
> My suggestion is to use a separate {{Node -> Integer}} (or {{Long}}?) Guava
> cache and use the long values instead to generate the cache key. Or any other
> more efficient datastructure, not even sure if a String is necessary?
> We tried some fix which works for us and keeps the memory consumption stable:
> {code:java}
> private LoadingCache<Node, Integer> nodeIDCache;
> private AtomicInteger cacheCounter;
> ...
> cacheCounter = new AtomicInteger(0);
> CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder();
> if (maxSize > 0) {
> builder = builder.maximumSize(maxSize);
> }
> if (expiryInterval > 0) {
> builder = builder.expireAfterWrite(expiryInterval,
> TimeUnit.MILLISECONDS);
> }
> nodeIDCache = builder.build(
> new CacheLoader<>() {
> public Integer load(Node key) {
> return cacheCounter.incrementAndGet();
> }
> });
> {code}
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