NPE using drools accumulate function in fairness constraint (tennis example) ---------------------------------------------------------------------------- Key: DROOLS-1686 URL: https://issues.jboss.org/browse/DROOLS-1686 Project: Drools Issue Type: Bug Components: core engine Affects Versions: 7.1.0.Final Environment: openjdk version "1.8.0_131" OpenJDK Runtime Environment (build 1.8.0_131-b11) OpenJDK 64-Bit Server VM (build 25.131-b11, mixed mode) Reporter: Markus Müller Assignee: Mario Fusco Attachments: TennisConstraintsTest.java Using the LoadBalanceAccumulateFunction found in tennis example for modelling fairness constraints leads to NPE in drools itself, in FromNodeLeftTuple.java: {code} Caused by: java.lang.NullPointerException at org.drools.core.reteoo.FromNodeLeftTuple.getAccumulatedObjects(FromNodeLeftTuple.java:98) {code} Full stacktrace: {code:java} Exception executing consequence for rule "fairAssignmentCountPerTeam" in org.optaplanner.examples.tennis.solver: java.lang.NullPointerException at org.drools.core.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39) at org.drools.core.common.DefaultAgenda.handleException(DefaultAgenda.java:1252) at org.drools.core.phreak.RuleExecutor.innerFireActivation(RuleExecutor.java:438) at org.drools.core.phreak.RuleExecutor.fireActivation(RuleExecutor.java:379) at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:135) at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:88) at org.drools.core.concurrent.AbstractRuleEvaluator.internalEvaluateAndFire(AbstractRuleEvaluator.java:34) at org.drools.core.concurrent.SequentialRuleEvaluator.evaluateAndFire(SequentialRuleEvaluator.java:43) at org.drools.core.common.DefaultAgenda.fireLoop(DefaultAgenda.java:1068) at org.drools.core.common.DefaultAgenda.internalFireAllRules(DefaultAgenda.java:1015) at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1007) at org.drools.core.impl.StatefulKnowledgeSessionImpl.internalFireAllRules(StatefulKnowledgeSessionImpl.java:1320) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1311) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1295) at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.calculateScore(DroolsScoreDirector.java:117) at org.optaplanner.test.impl.score.AbstractScoreVerifier.assertWeight(AbstractScoreVerifier.java:82) at org.optaplanner.test.impl.score.buildin.hardmediumsoft.HardMediumSoftScoreVerifier.assertSoftWeight(HardMediumSoftScoreVerifier.java:107) at org.optaplanner.test.impl.score.buildin.hardmediumsoft.HardMediumSoftScoreVerifier.assertSoftWeight(HardMediumSoftScoreVerifier.java:94) at org.optaplanner.examples.tennis.TennisConstraintsTest.fairAssignmentCountPerTeam(TennisConstraintsTest.java:40) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70) Caused by: java.lang.NullPointerException at org.drools.core.reteoo.FromNodeLeftTuple.getAccumulatedObjects(FromNodeLeftTuple.java:98) at org.drools.core.common.AgendaItem.getObjectsDeep(AgendaItem.java:78) at org.drools.core.reteoo.RuleTerminalNodeLeftTuple.getObjectsDeep(RuleTerminalNodeLeftTuple.java:359) at org.optaplanner.core.api.score.holder.AbstractScoreHolder.extractJustificationList(AbstractScoreHolder.java:118) at org.optaplanner.core.api.score.holder.AbstractScoreHolder.registerConstraintMatch(AbstractScoreHolder.java:88) at org.optaplanner.core.api.score.buildin.hardmediumsoft.HardMediumSoftScoreHolder.addMediumConstraintMatch(HardMediumSoftScoreHolder.java:69) at org.optaplanner.examples.tennis.solver.Rule_fairAssignmentCountPerTeam1005511081.defaultConsequence(Rule_fairAssignmentCountPerTeam1005511081.java:21) at org.optaplanner.examples.tennis.solver.Rule_fairAssignmentCountPerTeam1005511081DefaultConsequenceInvokerGenerated.evaluate(Unknown Source) at org.optaplanner.examples.tennis.solver.Rule_fairAssignmentCountPerTeam1005511081DefaultConsequenceInvoker.evaluate(Unknown Source) at org.drools.core.phreak.RuleExecutor.innerFireActivation(RuleExecutor.java:431) ... 38 more {code} See also related discussion in: https://groups.google.com/forum/#!topic/optaplanner-dev/xA6IdGieDpU