使用Pellet作為推理器的OutOfMemoryError

Question

我正在嘗試使用Pellet推斷數據，但由於“OutOfMemoryError：Java堆空間”，我的應用程序在推理期間總是崩潰。

正如其他地方所建議的，我已經嘗試增加堆大小，目前我正在使用這些VM參數：“ - XX：MaxPermSize = 256m -Xmx6144m”。 此外，我要設置'PelletOptions.USE_CONTINUOUS = true'，但到目前為止，我只能將崩潰延遲幾分鍾。 （到目前為止最長的運行時間：30分鍾）。

我將數據存儲在Jena TDB triplestore中。 它的總大小為170 MB，包含962117個語句。 本體已經在Protege中建模，並且在使用Hermit或Fact ++進行推理時沒有任何不一致（當然當時沒有數據存在）。 我想推斷的語句是使用等效類（例如：A和（hasX some X）），反向屬性（hasX < - > isXOf）和一些傳遞屬性建模的。 共有55個類：14個根類，11個等價類（一個根類的所有子類型）。 目前已將14個類的實例添加到tripestore中。

我也使用pellint來分析我的本體，但我不確定從這個結果得出哪些結論：

[Untyped classes]
- http://www.w3.org/2002/07/owl#AllDisjointClasses

[Untyped object roles]
- http://www.w3.org/2002/07/owl#topObjectPriority
- http://www.w3.org/2002/07/owl#members

[Untyped datatype roles]
- http://www.w3.org/2002/07/owl#qualifiedCardinality

[Untyped individuals]
- 4 BNodes

這是我創建InfModel的代碼：

 Dataset dataset = TDBFactory.createDataset(..);
 Model model = dataset.getDefaultModel();

 OntModel ont = ModelFactory.createOntologyModel(PelletReasonerFactory.THE_SPEC,model);
 ont.read("file:.." , "RDF/XML");

 PelletOptions.USE_CONTINUOUS_RULES = true;
 Reasoner reasoner = PelletReasonerFactory.theInstance().create();
 reasoner = reasoner.bindSchema(ont);

 InfModel infModel = infModel = ModelFactory.createInfModel(reasoner, model);

這基本上是我查詢數據的方式：

 QueryExecution qe = QueryExecutionFactory.create("SELECT ...", infModel);
 Resultset rs = qe.execSelect();

 while(rs.hasNext())
 {
     QuerySolution sol = rs.nextSolution();
     ...
 }
 qe.close();

如您所見，在查詢數據，准備或驗證InfModel時，我收到了各種異常。 你有任何想法，我還能嘗試解決這個錯誤嗎？

 java.lang.OutOfMemoryError: Java heap space
 at java.util.Arrays.copyOf(Unknown Source)
 at java.lang.AbstractStringBuilder.expandCapacity(Unknown Source)
 at java.lang.AbstractStringBuilder.append(Unknown Source)
 at java.lang.StringBuilder.append(Unknown Source)
 at java.net.URLStreamHandler.parseURL(Unknown Source)
 at sun.net.www.protocol.file.Handler.parseURL(Unknown Source)
 at java.net.URL.<init>(Unknown Source)
 at java.net.URL.<init>(Unknown Source)
 at sun.misc.URLClassPath$FileLoader.getResource(Unknown Source)
 at sun.misc.URLClassPath.getResource(Unknown Source)
 at java.net.URLClassLoader$1.run(Unknown Source)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(Unknown Source)
 at java.lang.ClassLoader.loadClass(Unknown Source)
 at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
 at java.lang.ClassLoader.loadClass(Unknown Source)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorCheck.warn(QueryIteratorCheck.java:114)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorCheck.dump(QueryIteratorCheck.java:95)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorCheck.checkForOpenIterators(QueryIteratorCheck.java:68)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorCheck.close(QueryIteratorCheck.java:50)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorWrapper.closeIterator(QueryIteratorWrapper.java:50)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorBase.close(QueryIteratorBase.java:184)
 at com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorCloseable.close(QueryIteratorCloseable.java:39)
 at com.hp.hpl.jena.sparql.engine.QueryExecutionBase.close(QueryExecutionBase.java:180)


 java.lang.OutOfMemoryError: Java heap space
 at shared.SharedObjectFactory.build(SharedObjectFactory.java:303)
 at aterm.pure.PureFactory.makeAppl(PureFactory.java:191)
 at aterm.pure.PureFactory.makeAppl(PureFactory.java:185)
 at aterm.pure.PureFactory.makeAppl(PureFactory.java:228)
 at org.mindswap.pellet.utils.ATermUtils.makeLiteral(ATermUtils.java:245)
 at org.mindswap.pellet.ABox.addLiteral(ABox.java:1696)
 at org.mindswap.pellet.tableau.completion.rule.SomeValuesRule.applySomeValuesRule(SomeValuesRule.java:174)
 at org.mindswap.pellet.tableau.completion.rule.SomeValuesRule.apply(SomeValuesRule.java:64)
 at org.mindswap.pellet.tableau.completion.rule.AbstractTableauRule.apply(AbstractTableauRule.java:64)
 at org.mindswap.pellet.tableau.completion.SROIQStrategy.complete(SROIQStrategy.java:157)
 at org.mindswap.pellet.ABox.isConsistent(ABox.java:1423)
 at org.mindswap.pellet.ABox.isConsistent(ABox.java:1260)
 at org.mindswap.pellet.KnowledgeBase.consistency(KnowledgeBase.java:1987)
 at org.mindswap.pellet.KnowledgeBase.isConsistent(KnowledgeBase.java:2061)
 at org.mindswap.pellet.jena.PelletInfGraph.prepare(PelletInfGraph.java:247)
 at org.mindswap.pellet.jena.PelletInfGraph.prepare(PelletInfGraph.java:230)
 at com.hp.hpl.jena.rdf.model.impl.InfModelImpl.prepare(InfModelImpl.java:89)


 java.lang.OutOfMemoryError: Java heap space
 at org.mindswap.pellet.tableau.branch.DisjunctionBranch.tryBranch(DisjunctionBranch.java:197)
 at org.mindswap.pellet.tableau.branch.Branch.tryNext(Branch.java:117)
 at org.mindswap.pellet.tableau.completion.rule.ChooseRule.apply(ChooseRule.java:82)
 at org.mindswap.pellet.tableau.completion.rule.ChooseRule.apply(ChooseRule.java:56)
 at org.mindswap.pellet.tableau.completion.rule.AbstractTableauRule.apply(AbstractTableauRule.java:64)
 at org.mindswap.pellet.tableau.completion.SROIQStrategy.complete(SROIQStrategy.java:157)
 at org.mindswap.pellet.ABox.isConsistent(ABox.java:1423)
 at org.mindswap.pellet.ABox.isConsistent(ABox.java:1260)
 at org.mindswap.pellet.KnowledgeBase.consistency(KnowledgeBase.java:1987)
 at org.mindswap.pellet.KnowledgeBase.isConsistent(KnowledgeBase.java:2061)
 at org.mindswap.pellet.jena.PelletInfGraph.prepare(PelletInfGraph.java:247)
 at org.mindswap.pellet.jena.PelletInfGraph.prepare(PelletInfGraph.java:230)
 at org.mindswap.pellet.jena.PelletInfGraph.validate(PelletInfGraph.java:564)
 at com.hp.hpl.jena.rdf.model.impl.InfModelImpl.validate(InfModelImpl.java:111)

Answer 1

查詢infModel顯然導致Pellet生成了數百個owl:differentFrom of owl:differentFrom語句。 解決方案是使用ModelExtractor ：

ModelExtractor ext = new ModelExtractor(inf); 
Model m = ext.extractModel();
QueryExecution qe = QueryExecutionFactory.create("SELECT ...", m);