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  1. Apache Jena
  2. JENA-1294

JenaSystem.init from RDFS throws NPE, fails ARQ tests



    • Type: Bug
    • Status: Closed
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: Jena 3.2.0
    • Fix Version/s: Jena 3.3.0
    • Component/s: ARQ, Core
    • Labels:
    • Environment:

      OpenJDK 1.8.0_121-b13
      Linux 4.9.8-1-ARCH #1 SMP PREEMPT x86_64 GNU/Linux


      As discussed in #JENA-1290, jena-arq tests failed but committers could not reproduce the issue. The cause was that for some reason the first test that ran on was TestParameterizedSparqlString.test_param_string_injection_01, and as the following stack trace shows, it reached JenaSystem.init from RDFS class initialization.

      At least 3 locations involved in core and ARQ initalization refer to RDFS.subClassOf and RDFS.member which are null and cannot be initialized because RDFS is already being initialized:

      Init: JenaInitLevel0
      Init: InitJenaCore
      JenaCore.init - start
      RDF: http://www.w3.org/1999/02/22-rdf-syntax-ns#
      RDFS: http://www.w3.org/2000/01/rdf-schema#
      RDFS.subClassOf: null
      OWL: http://www.w3.org/2002/07/owl#
      JenaCore.init - finish
      Init: InitRIOT
      RIOT.init - start
      RIOT.init - finish
      Init: InitARQ
      ARQ.init - start
      ARQ.init - start.1
      ARQ.init - start.2
      ARQ.init - start.3
      ARQ.init - start.4
      AssemblerUtils.init - start
      AssemblerUtils.init.registerDataset - start
      RDFS.subClassOf==null: true
      nulls: 5876a9af 7993aa96 null e1204e1f
      	at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1192)
      	at org.apache.jena.assembler.assemblers.AssemblerGroup$ExpandingAssemblerGroup.implementWith(AssemblerGroup.java:95)
      	at org.apache.jena.assembler.ConstAssembler.general(ConstAssembler.java:137)
      	at org.apache.jena.sparql.core.assembler.AssemblerUtils.registerDataset(AssemblerUtils.java:72)
      	at org.apache.jena.sparql.core.assembler.AssemblerUtils.init(AssemblerUtils.java:61)
      	at org.apache.jena.query.ARQ.init(ARQ.java:596)
      	at org.apache.jena.sparql.system.InitARQ.start(InitARQ.java:29)
      	at org.apache.jena.system.JenaSystem.lambda$init$2(JenaSystem.java:119)
      	at java.util.ArrayList.forEach(ArrayList.java:1249)
      	at org.apache.jena.system.JenaSystem.forEach(JenaSystem.java:194)
      	at org.apache.jena.system.JenaSystem.forEach(JenaSystem.java:171)
      	at org.apache.jena.system.JenaSystem.init(JenaSystem.java:117)
      	at org.apache.jena.graph.NodeFactory.<clinit>(NodeFactory.java:32)
      	at org.apache.jena.rdf.model.impl.ResourceImpl.fresh(ResourceImpl.java:135)
      	at org.apache.jena.rdf.model.impl.ResourceImpl.<init>(ResourceImpl.java:85)
      	at org.apache.jena.rdf.model.ResourceFactory$Impl.createResource(ResourceFactory.java:297)
      	at org.apache.jena.rdf.model.ResourceFactory.createResource(ResourceFactory.java:92)
      	at org.apache.jena.vocabulary.RDFS.resource(RDFS.java:36)
      	at org.apache.jena.vocabulary.RDFS.<clinit>(RDFS.java:44)
      	at org.apache.jena.shared.PrefixMapping.<clinit>(PrefixMapping.java:219)
      	at org.apache.jena.query.TestParameterizedSparqlString.test_param_string_injection_01(TestParameterizedSparqlString.java:1382)

      The same problem can be observed on a one-liner mwe (jena-rdfs-init):

      public class App {
          public static void main(String[] args) {
              System.out.printf("subClassOf URI: %s\n", RDFS.subClassOf.toString());

      The ARQ test issue can be fixed adding a call to JenaSystem.init (call-init.patch). However, if test order changes for someone, the problem re-appears.

      For Both the MWE and the test, replacing RDFS fields used in init code with RDF.getURI()+"localName" fixes it (no-rdfs-on-init.patch). It is a hack and the problem remains for if the MWE uses vocab classes (RDF and OWL) in place of RDFS.


        1. call-init.patch
          1 kB
          Alexis Armin Huf
        2. jena-rdfs-init.tar.gz
          10 kB
          Alexis Armin Huf
        3. mvn-verify-arq-bug.log.gz
          65 kB
          Alexis Armin Huf
        4. no-rdfs-on-init.patch
          3 kB
          Alexis Armin Huf
        5. testInitFromRDFS.patch
          2 kB
          Alexis Armin Huf

          Issue Links



              • Assignee:
                andy Andy Seaborne
                alexishuf Alexis Armin Huf
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                • Created: