Missing synchronization in PackageClassLoader causes a LinkageError: duplicate class definition ----------------------------------------------------------------------------------------------- Key: DROOLS-926 URL: https://issues.jboss.org/browse/DROOLS-926 Project: Drools Issue Type: Bug Reporter: Mario Fusco Assignee: Mario Fusco Fix For: 6.3.0.Final Creating multiple KieSessions from a KieBase with a function and using them concurrently from different threads may lead to the following error java.util.concurrent.ExecutionException: java.lang.LinkageError: loader (instance of org/drools/core/rule/JavaDialectRuntimeData$PackageClassLoader): attempted duplicate class definition for name: "defaultpkg/IsEven" at java.util.concurrent.FutureTask.report(FutureTask.java:122) at java.util.concurrent.FutureTask.get(FutureTask.java:188) at org.drools.compiler.integrationtests.Misc2Test.testFunctionInvokingFunction(Misc2Test.java:8191) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) at org.junit.runner.JUnitCore.run(JUnitCore.java:160) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:78) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:212) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:68) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140) Caused by: java.lang.LinkageError: loader (instance of org/drools/core/rule/JavaDialectRuntimeData$PackageClassLoader): attempted duplicate class definition for name: "defaultpkg/IsEven" at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:800) at org.drools.core.rule.JavaDialectRuntimeData$PackageClassLoader.fastFindClass(JavaDialectRuntimeData.java:673) at org.drools.core.rule.JavaDialectRuntimeData$PackageClassLoader.loadClass(JavaDialectRuntimeData.java:639) at java.lang.ClassLoader.loadClass(ClassLoader.java:358) at org.drools.core.rule.MVELDialectRuntimeData.getParserConfiguration(MVELDialectRuntimeData.java:299) at org.drools.core.base.mvel.MVELCompilationUnit.getCompiledExpression(MVELCompilationUnit.java:214) at org.drools.core.rule.constraint.MvelConstraint.createMvelConditionEvaluator(MvelConstraint.java:254) at org.drools.core.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:238) at org.drools.core.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:204) at org.drools.core.reteoo.AlphaNode.assertObject(AlphaNode.java:141) at org.drools.core.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:60) at org.drools.core.reteoo.ObjectTypeNode.propagateAssert(ObjectTypeNode.java:298) at org.drools.core.phreak.PropagationEntry$Insert.execute(PropagationEntry.java:93) at org.drools.core.phreak.SynchronizedPropagationList.flush(SynchronizedPropagationList.java:96) at org.drools.core.phreak.SynchronizedPropagationList.flush(SynchronizedPropagationList.java:69) at org.drools.core.impl.StatefulKnowledgeSessionImpl.flushPropagations(StatefulKnowledgeSessionImpl.java:1993) at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1289) at org.drools.core.impl.StatefulKnowledgeSessionImpl.internalFireAllRules(StatefulKnowledgeSessionImpl.java:1294) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1281) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1260) at org.drools.compiler.integrationtests.Misc2Test$11.call(Misc2Test.java:8180) at org.drools.compiler.integrationtests.Misc2Test$11.call(Misc2Test.java:8170) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask.run(FutureTask.java:262) 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:745)