[jboss-jira] [JBoss JIRA] (JBRULES-3552) ConcurrentModificationException in CompositeClassLoader$CachingLoader in multithreading environment
Mario Fusco (JIRA)
jira-events at lists.jboss.org
Tue Sep 25 06:07:34 EDT 2012
[ https://issues.jboss.org/browse/JBRULES-3552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12721332#comment-12721332 ]
Mario Fusco commented on JBRULES-3552:
--------------------------------------
In theory I see the problem and probably it could be trivially fixed by replacing that HashMap with a Concurrent one.
Anyway I don't like to do "blind" fixes and I wish I could be able to reproduce this issue at least once before to fix it.
Unfortunately following your instruction I haven't been able to reproduce this.
Said that I understand this is a race condition and the ConcurrentModificationException won't be raised in the 100% of cases, could you please provide a very simple unit test allowing me to reproduce it?
Thanks,
Mario
> ConcurrentModificationException in CompositeClassLoader$CachingLoader in multithreading environment
> ---------------------------------------------------------------------------------------------------
>
> Key: JBRULES-3552
> URL: https://issues.jboss.org/browse/JBRULES-3552
> Project: Drools
> Issue Type: Bug
> Security Level: Public(Everyone can see)
> Components: drools-api
> Affects Versions: 5.4.0.Final
> Environment: drools expert, ejb, application server
> Reporter: Peter P
> Assignee: Mark Proctor
>
> Sometimes we get this exception when executing rules from multiple threads at first time after application server starts, probably same rule file.
> Here is our environment:
> 1. We are using precompiled knowledge base by serialized into file and deserialize it from file when using it;
> 2. Use same knowledge base object for all threads;
> 3. Call newStatelessKnowledgeSession from same knowledge base for every thread when executing rules;
> 4. stateless session is never cached or shared among threads;
> Following are stack trace:
> [java.util.ConcurrentModificationException] concurrent access to HashMap attempted by Thread[ORB.thread.pool :
> 3,5,main]
> at java.util.HashMap.onExit(HashMap.java:226)
> at java.util.HashMap.transfer(HashMap.java:690)
> at java.util.HashMap.resize(HashMap.java:676)
> at java.util.HashMap.addEntry(HashMap.java:1049)
> at java.util.HashMap.put(HashMap.java:561)
> at org.drools.util.CompositeClassLoader$CachingLoader.load(CompositeClassLoader.java:271)
> at org.drools.util.CompositeClassLoader$CachingLoader.load(CompositeClassLoader.java:237)
> at org.drools.util.CompositeClassLoader.loadClass(CompositeClassLoader.java:88)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:597)
> at java.lang.Class.forNameImpl(Native Method)
> at java.lang.Class.forName(Class.java:163)
> at org.mvel2.ParserConfiguration.checkForDynamicImport(ParserConfiguration.java:159)
> at org.mvel2.ParserConfiguration.hasImport(ParserConfiguration.java:187)
> at org.mvel2.ParserContext.hasImport(ParserContext.java:352)
> at org.mvel2.compiler.PropertyVerifier.getBeanProperty(PropertyVerifier.java:163)
> at org.mvel2.compiler.PropertyVerifier.analyze(PropertyVerifier.java:117)
> at org.mvel2.compiler.ExpressionCompiler.verify(ExpressionCompiler.java:381)
> at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:273)
> at org.mvel2.util.ParseTools.subCompileExpression(ParseTools.java:2137)
> at org.mvel2.ast.Substatement.<init>(Substatement.java:38)
> at org.mvel2.compiler.AbstractParser.nextToken(AbstractParser.java:1073)
> at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:128)
> at org.mvel2.util.ParseTools.subCompileExpression(ParseTools.java:2137)
> at org.mvel2.ast.Negation.<init>(Negation.java:40)
> at org.mvel2.compiler.AbstractParser.nextToken(AbstractParser.java:1181)
> at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:128)
> at org.mvel2.compiler.ExpressionCompiler.compile(ExpressionCompiler.java:62)
> at org.mvel2.MVEL.compileExpression(MVEL.java:810)
> at org.drools.base.mvel.MVELCompilationUnit.compile(MVELCompilationUnit.java:442)
> at org.drools.base.mvel.MVELCompilationUnit.getCompiledExpression(MVELCompilationUnit.java:238)
> at org.drools.rule.constraint.MvelConstraint.createMvelConditionEvaluator(MvelConstraint.java:173)
> at org.drools.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:157)
> at org.drools.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:124)
> at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:137)
> at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497)
> at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:382)
> at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:235)
> at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:240)
> at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:337)
> at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:298)
> at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:888)
> at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:847)
> at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:269)
> at org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:303)
> at com.validators.Validator.execute(Validator.java:436)
> at com.ejb.EJBBean.validate(EJBBean.java:122)
> at com.ejb._EJSRemote0SLEJBBean_3a6166f4_Tie.validate(_EJSRemote0SLEJBBean_3a6166f4_Tie.java)
> at com.ibm.CORBA.iiop.ServerDelegate.dispatchInvokeHandler(ServerDelegate.java:621)
> at com.ibm.CORBA.iiop.ServerDelegate.dispatch(ServerDelegate.java:474)
> at com.ibm.rmi.iiop.ORB.process(ORB.java:503)
> at com.ibm.CORBA.iiop.ORB.process(ORB.java:1571)
> at com.ibm.rmi.iiop.Connection.respondTo(Connection.java:2703)
> at com.ibm.rmi.iiop.Connection.doWork(Connection.java:2577)
> at com.ibm.rmi.iiop.WorkUnitImpl.doWork(WorkUnitImpl.java:62)
> at com.ibm.ejs.oa.pool.PooledThread.run(ThreadPool.java:118)
> at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1551)
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