jena pellet intermittent issues

RROR [http-bio-8081-exec-676] (SemantEcoServlet.java:410) - Invalid target for invocation java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at edu.rpi.tw.escience.semanteco.SemantEcoServlet.invokeHierarchyMethod(SemantEcoServlet.java:351) at edu.rpi.tw.escience.semanteco.SemantEcoServlet.invokeRestCall(SemantEcoServlet.java:382) at edu.rpi.tw.escience.semanteco.SemantEcoServlet.doGet(SemantEcoServlet.java:217) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at edu.rpi.tw.escience.semanteco.CacheControlFilter.doFilter(CacheControlFilter.java:49) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:722) Caused by: java.util.ConcurrentModificationException at com.hp.hpl.jena.mem.ArrayBunch$2.hasNext(ArrayBunch.java:109) at com.hp.hpl.jena.util.iterator.WrappedIterator.hasNext(WrappedIterator.java:64) at com.hp.hpl.jena.util.iterator.FilterIterator.hasNext(FilterIterator.java:43) at com.hp.hpl.jena.util.iterator.WrappedIterator.hasNext(WrappedIterator.java:64) at com.hp.hpl.jena.util.iterator.NiceIterator$1.hasNext(NiceIterator.java:86) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.getObject(DefaultGraphLoader.java:257) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.isRestriction(DefaultGraphLoader.java:343) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.node2term(DefaultGraphLoader.java:546) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.processType(DefaultGraphLoader.java:1246) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.processTypes(DefaultGraphLoader.java:1208) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.processTypes(DefaultGraphLoader.java:1186) at org.mindswap.pellet.jena.graph.loader.DefaultGraphLoader.load(DefaultGraphLoader.java:2082) at org.mindswap.pellet.jena.PelletInfGraph.load(PelletInfGraph.java:210) at org.mindswap.pellet.jena.PelletInfGraph.prepare(PelletInfGraph.java:258) at org.mindswap.pellet.jena.PelletInfGraph.prepare(PelletInfGraph.java:246) at org.mindswap.pellet.jena.PelletInfGraph.containsTriple(PelletInfGraph.java:482) at org.mindswap.pellet.jena.PelletInfGraph.graphBaseContains(PelletInfGraph.java:335) at com.hp.hpl.jena.graph.impl.GraphBase.contains(GraphBase.java:270) at com.hp.hpl.jena.graph.impl.GraphBase.contains(GraphBase.java:296) at com.hp.hpl.jena.ontology.impl.OWLProfile$SupportsCheck.hasType(OWLProfile.java:277) at com.hp.hpl.jena.ontology.impl.OWLProfile$3.doCheck(OWLProfile.java:331) at com.hp.hpl.jena.ontology.impl.OWLProfile.isSupported(OWLProfile.java:199) at com.hp.hpl.jena.ontology.impl.OntClassImpl$1.canWrap(OntClassImpl.java:90) at com.hp.hpl.jena.ontology.impl.OntClassImpl$1.wrap(OntClassImpl.java:78) at com.hp.hpl.jena.enhanced.EnhNode.convertTo(EnhNode.java:142) at com.hp.hpl.jena.enhanced.EnhNode.convertTo(EnhNode.java:22) at com.hp.hpl.jena.enhanced.Polymorphic.asInternal(Polymorphic.java:54) at com.hp.hpl.jena.enhanced.EnhNode.as(EnhNode.java:97) at com.hp.hpl.jena.ontology.impl.OntResourceImpl$SubjectAsMapper.map1(OntResourceImpl.java:1588) at com.hp.hpl.jena.ontology.impl.OntResourceImpl$SubjectAsMapper.map1(OntResourceImpl.java:1583) at com.hp.hpl.jena.util.iterator.Map1Iterator.next(Map1Iterator.java:35) at com.hp.hpl.jena.util.iterator.WrappedIterator.next(WrappedIterator.java:68) at com.hp.hpl.jena.util.iterator.UniqueExtendedIterator.nextIfNew(UniqueExtendedIterator.java:61) at com.hp.hpl.jena.util.iterator.UniqueExtendedIterator.hasNext(UniqueExtendedIterator.java:69) at com.hp.hpl.jena.util.iterator.WrappedIterator.hasNext(WrappedIterator.java:64) at com.hp.hpl.jena.util.iterator.FilterIterator.hasNext(FilterIterator.java:43) at com.hp.hpl.jena.util.iterator.WrappedIterator.hasNext(WrappedIterator.java:64) at com.hp.hpl.jena.util.iterator.UniqueExtendedIterator.hasNext(UniqueExtendedIterator.java:69) at edu.rpi.tw.escience.semanteco.annotator.AnnotatorModule.queryAnnotatorClassHMRoots(AnnotatorModule.java:1451) at edu.rpi.tw.escience.semanteco.annotator.AnnotatorModule.queryAnnotatorClassHM(AnnotatorModule.java:1326) ... 28 more