RuleEngine AfterEvaluator.evaluateCachedRight throws NPE on persisted Session reload (Phreak, Stream, PseudoClock) ------------------------------------------------------------------------------------------------------------------ Key: DROOLS-275 URL: https://issues.jboss.org/browse/DROOLS-275 Project: Drools Issue Type: Bug Security Level: Public(Everyone can see) Affects Versions: 6.0.0.CR3 Environment: Mac OS-X 10.8.5, Hotspot 1.7.0_40 Reporter: Duncan Doyle Assignee: Mario Fusco Fix For: 6.0.0.CR5 I persist a KieSession via the Marshaller (serializable) with one fact/event inserted. On reload of the session, I can see that fact is still there (when I check the FactHandles) and the PseudoClock is at the correct time (the time when I persisted it). If I then insert another fact/event into this reloaded session which matches the following rule: rule "SimpleFactTimeWindow" when $s1: SimpleFact() from entry-point LinkyStream $s2: SimpleFact(this != $s1, this after [0s, 10s] $s1) from entry-point LinkyStream then System.out.println("Rule fired, found 2 Facts within the time window."); end I get a NPE (in both Phreak and ReteOO mode). Exception in Phreak: 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:606) at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297) at java.lang.Thread.run(Thread.java:724) Caused by: java.lang.NullPointerException at org.drools.core.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedRight(AfterEvaluatorDefinition.java:304) at org.drools.core.rule.constraint.EvaluatorConstraint.isAllowedCachedRight(EvaluatorConstraint.java:80) at org.drools.core.common.DoubleBetaConstraints.isAllowedCachedRight(DoubleBetaConstraints.java:117) at org.drools.core.phreak.PhreakJoinNode.doRightInserts(PhreakJoinNode.java:150) at org.drools.core.phreak.PhreakJoinNode.doNode(PhreakJoinNode.java:56) at org.drools.core.phreak.RuleNetworkEvaluator.switchOnDoBetaNode(RuleNetworkEvaluator.java:547) at org.drools.core.phreak.RuleNetworkEvaluator.evalBetaNode(RuleNetworkEvaluator.java:533) at org.drools.core.phreak.RuleNetworkEvaluator.innerEval(RuleNetworkEvaluator.java:335) at org.drools.core.phreak.RuleNetworkEvaluator.outerEval(RuleNetworkEvaluator.java:162) at org.drools.core.phreak.RuleNetworkEvaluator.evaluateNetwork(RuleNetworkEvaluator.java:117) at org.drools.core.phreak.RuleExecutor.reEvaluateNetwork(RuleExecutor.java:194) at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:65) at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:936) at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1183) at org.drools.core.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:936) at org.drools.core.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:910) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:233) at org.jboss.ddoyle.brms.cep.ha.management.TestScenarioRunner.secondRun(TestScenarioRunner.java:142) at org.jboss.ddoyle.brms.cep.ha.management.MainSecondRun.main(MainSecondRun.java:7) ... 6 more Exception in ReteOO: 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:606) at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297) at java.lang.Thread.run(Thread.java:724) Caused by: org.drools.core.RuntimeDroolsException: Unexpected exception executing action org.drools.core.reteoo.PropagationQueuingNode$PropagateAction@2e3aeda at org.drools.core.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1225) at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:371) at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:278) at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:131) at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:56) at org.jboss.ddoyle.brms.cep.ha.management.TestScenarioRunner.secondRun(TestScenarioRunner.java:140) at org.jboss.ddoyle.brms.cep.ha.management.MainSecondRun.main(MainSecondRun.java:7) ... 6 more Caused by: java.lang.NullPointerException at org.drools.core.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:324) at org.drools.core.rule.constraint.EvaluatorConstraint.isAllowedCachedLeft(EvaluatorConstraint.java:67) at org.drools.core.common.DoubleBetaConstraints.isAllowedCachedLeft(DoubleBetaConstraints.java:108) at org.drools.reteoo.nodes.ReteJoinNode.propagateFromLeft(ReteJoinNode.java:147) at org.drools.reteoo.nodes.ReteJoinNode.assertLeftTuple(ReteJoinNode.java:99) at org.drools.core.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:213) at org.drools.core.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:73) at org.drools.reteoo.nodes.ReteJoinNode.propagateFromRight(ReteJoinNode.java:135) at org.drools.reteoo.nodes.ReteJoinNode.assertRightTuple(ReteJoinNode.java:125) at org.drools.reteoo.nodes.ReteBetaNodeUtils.assertObject(ReteBetaNodeUtils.java:47) at org.drools.reteoo.nodes.ReteJoinNode.assertObject(ReteJoinNode.java:39) at org.drools.core.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:502) at org.drools.core.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:387) at org.drools.core.reteoo.PropagationQueuingNode$AssertAction.execute(PropagationQueuingNode.java:430) at org.drools.core.reteoo.PropagationQueuingNode.propagateActions(PropagationQueuingNode.java:266) at org.drools.core.reteoo.PropagationQueuingNode$PropagateAction.execute(PropagationQueuingNode.java:592) at org.drools.core.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1223) ... 12 more What I discovered is that this only happens when I save the KieSession to a file in one JVM and reload it in another. When I load the KieSession in the same JVM as the one in which I persisted it, there is no exception and the rule get's fired (as expected). I created a reproducer project for it: https://github.com/DuncanDoyle/DroolsSessionPersistenceNPE/ I've added some Maven profiles so you can easily observe the behaviour: - mvn -PallRuns exec:java : this runs both the persistence and the reload in the same JVM, no exception, everything works fine. - mvn -PfirstRun exec:java : this runs the first part of the test, and saves the KieSession to a file. - mvn -PsecondRun exec:java : this runs the second part of the test, which loads the previously saved KieSession from the file and inserts a new fact, resulting in the NPE. All three tests can also be run in ReteOO mode by adding "-Ddrools.ruleEngine=reteoo" at the end of the command.