Incremental Builds Result in ClassCastExceptions ------------------------------------------------ Key: DROOLS-323 URL: https://issues.jboss.org/browse/DROOLS-323 Project: Drools Issue Type: Bug Security Level: Public(Everyone can see) Affects Versions: 5.5.0.Final Reporter: David Templin Assignee: Mark Proctor Attachments: drools-bug.tar.gz Incremental builds via the {{KnowledgeAgent}} occasionally result in a {{ClassCastException}}, such as the following: {noformat} 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$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:695) {noformat} Steps to reproduce: # Download the attached zip file ({{drools-bug.tar.gz}}) # Extract the contents into a directory # {{cd <directory>}} # {{mvn install}} # Type {{sh target/classes/run.sh}}, or else type {{java -classpath target/classes:target/lib/* -javaagent:target/lib/aspectjweaver-1.7.3.jar com.foo.Main}} # Wait for a sequence of log messages similar to the following messages to begin to print to the console: {noformat} [2013-11-06 11:05:33,742:debug] ResourceChangeScanner attempt to scan 1 resources [2013-11-06 11:05:33,743:debug] ResourceChangeScanner thread is waiting for 2 seconds. {noformat} # Edit {{target/classes/recommendations.drl}} in some trivial manner; for instance, I have found that editing the RHS of rule "Initialize Recommendations" by adding a print statement ({{e.g. System.out.println("test");}}) and editing the print statement a few times will reliably reproduce the problem; occasionally, merely touching the file will cause the problem to manifest. # Wait for the exception to print to the console; it will look like the exception above Note that the exception is suppressed by the executor architecture in Drools. Thus, I had to weave an aspect that catches the exception and prints it. This bug also results in a memory leak, since the {{ResourceChangeNotifier}} continues to produce {{ChangeSet}} objects, but there are no consumers after the {{ChangeSetNotificationDetector}} thread terminates, resulting in an unbounded queue. I also noticed the following exception in development, yet was unable to reproduce it in the attached demonstration project: {noformat} java.lang.ClassCastException: com.foo.AidAgreement cannot be cast to com.foo.Unit at org.drools.base.com.foo.Unit1155259690$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) {noformat} 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.