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Bug
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Resolution: Done
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Major
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5.5.0.Final
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None
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None
Incremental builds via the KnowledgeAgent occasionally result in a ClassCastException, such as the following:
java.lang.ClassCastException: org.drools.reteoo.AlphaNode$AlphaMemory cannot be cast to org.drools.reteoo.BetaMemory at org.drools.reteoo.JoinNode.updateSink(JoinNode.java:398) at org.drools.reteoo.RuleTerminalNode.attach(RuleTerminalNode.java:346) at org.drools.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:174) at org.drools.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:134) at org.drools.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:113) at org.drools.reteoo.ReteooRuleBase.addRule(ReteooRuleBase.java:445) at org.drools.common.AbstractRuleBase.addRule(AbstractRuleBase.java:952) at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:629) at org.drools.reteoo.ReteooRuleBase.addPackages(ReteooRuleBase.java:472) at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:149) at org.drools.agent.impl.KnowledgeAgentImpl.addResourcesToKnowledgeBase(KnowledgeAgentImpl.java:1117) at org.drools.agent.impl.KnowledgeAgentImpl.incrementalBuildResources(KnowledgeAgentImpl.java:1003) at org.drools.agent.impl.KnowledgeAgentImpl.buildKnowledgeBase(KnowledgeAgentImpl.java:686) at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:207) at org.drools.agent.impl.KnowledgeAgentImpl$ChangeSetNotificationDetector.run_aroundBody0(KnowledgeAgentImpl.java:1301) at org.drools.agent.impl.KnowledgeAgentImpl$ChangeSetNotificationDetector$AjcClosure1.run(KnowledgeAgentImpl.java:1) at com.foo.DroolsBugAspect.ajc$around$com_foo_DroolsBugAspect$1$b7e32854proceed(DroolsBugAspect.aj:8) at com.foo.DroolsBugAspect.ajc$around$com_foo_DroolsBugAspect$1$b7e32854(DroolsBugAspect.aj:10) at org.drools.agent.impl.KnowledgeAgentImpl$ChangeSetNotificationDetector.run(KnowledgeAgentImpl.java:1295) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:695)
Steps to reproduce:
- Download the attached zip file (drools-bug.tar.gz)
- Extract the contents into a directory
- cd <directory>
- mvn install
- Type sh target/classes/run.sh, or else type java -classpath target/classes:target/lib/* -javaagent:target/lib/aspectjweaver-1.7.3.jar com.foo.Main
- Wait for a sequence of log messages similar to the following messages to begin to print to the console:
[2013-11-06 11:05:33,742:debug] ResourceChangeScanner attempt to scan 1 resources [2013-11-06 11:05:33,743:debug] ResourceChangeScanner thread is waiting for 2 seconds.
- Edit target/classes/recommendations.drl in some trivial manner; for instance, I have found that editing the RHS of rule "Initialize Recommendations" by adding a print statement (e.g. System.out.println("test");) and editing the print statement a few times will reliably reproduce the problem; occasionally, merely touching the file will cause the problem to manifest.
- Wait for the exception to print to the console; it will look like the exception above
Note that the exception is suppressed by the executor architecture in Drools. Thus, I had to weave an aspect that catches the exception and prints it.
This bug also results in a memory leak, since the ResourceChangeNotifier continues to produce ChangeSet objects, but there are no consumers after the ChangeSetNotificationDetector thread terminates, resulting in an unbounded queue.
I also noticed the following exception in development, yet was unable to reproduce it in the attached demonstration project:
java.lang.ClassCastException: com.foo.AidAgreement cannot be cast to com.foo.Unit at org.drools.base.com.foo.Unit1155259690$getAgency.getValue(Unknown Source) at org.drools.base.extractors.BaseObjectClassFieldReader.getHashCode(BaseObjectClassFieldReader.java:204) at org.drools.base.ClassFieldReader.getHashCode(ClassFieldReader.java:193) at org.drools.core.util.AbstractHashTable$SingleIndex.hashCodeOf(AbstractHashTable.java:521) at org.drools.core.util.index.RightTupleIndexHashTable.getOrCreate(RightTupleIndexHashTable.java:438) at org.drools.core.util.index.RightTupleIndexHashTable.add(RightTupleIndexHashTable.java:319) at org.drools.reteoo.JoinNode.assertObject(JoinNode.java:136) at org.drools.reteoo.ObjectTypeNode.updateSink(ObjectTypeNode.java:334) at org.drools.reteoo.BetaNode.attach(BetaNode.java:408) at org.drools.reteoo.builder.BuildUtils.attachNode(BuildUtils.java:145) at org.drools.reteoo.builder.GroupElementBuilder$AndBuilder.build(GroupElementBuilder.java:142) at org.drools.reteoo.builder.GroupElementBuilder.build(GroupElementBuilder.java:70) at org.drools.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:161) at org.drools.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:134) at org.drools.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:113) at org.drools.reteoo.ReteooRuleBase.addRule(ReteooRuleBase.java:445) at org.drools.common.AbstractRuleBase.addRule(AbstractRuleBase.java:952) at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:629) at org.drools.reteoo.ReteooRuleBase.addPackages(ReteooRuleBase.java:472) at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:149) at org.drools.agent.impl.KnowledgeAgentImpl.addResourcesToKnowledgeBase(KnowledgeAgentImpl.java:1117) at org.drools.agent.impl.KnowledgeAgentImpl.incrementalBuildResources(KnowledgeAgentImpl.java:1003) at org.drools.agent.impl.KnowledgeAgentImpl.buildKnowledgeBase(KnowledgeAgentImpl.java:686) at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:207) at org.drools.agent.impl.KnowledgeAgentImpl$ChangeSetNotificationDetector.run_aroundBody0(KnowledgeAgentImpl.java:1301) at org.drools.agent.impl.KnowledgeAgentImpl$ChangeSetNotificationDetector$AjcClosure1.run(KnowledgeAgentImpl.java:1) at com.foo.DroolsBugAspect.ajc$around$com.foo_DroolsBugAspect$1$b7e32854proceed(DroolsBugAspect.aj:8) at com.foo.DroolsBugAspect.ajc$around$com.foo_DroolsBugAspect$1$b7e32854(DroolsBugAspect.aj:10) at org.drools.agent.impl.KnowledgeAgentImpl$ChangeSetNotificationDetector.run(KnowledgeAgentImpl.java:1295) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:695)
The demonstration code is, of course, only intended to demonstrate the problem. It is a highly simplified and slightly sanitized version of actual code that is in development.
