@David- thanks for your reply. In the patch, we have applied synchronise block, we referred to 6.0.0 release. Still it's throwing LinkageError for the same, Regards, Karan From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Davide Sottara Sent: 05 April 2014 12:19 To: rules-users(a)lists.jboss.org Subject: Re: [rules-users] Linkage Error In execute method Can you upgrade to 5.6? Otherwise, you'll have to synchronize the methods int ClassLoader, the null check is not enough On 04/04/2014 09:16 PM, Karan Malhotra wrote: Hi All, We have recently upgraded our application from 5.1.0 to 5.4.0.Final. Everything worked well until this was deployed at Production Envr. We started getting multiple Linkage Error in execute method of Stateless KnowledgeSession. StackTrace: Exception: java.util.concurrent.ExecutionException: java.lang.LinkageError: loader (instance oforg/drools/rule/JavaDialectRuntimeData$PackageClassLoader): attemptedduplicate class definition for name: "OffBarCapping/Rule_Off_Bar_Tariff_Capping_13_2a4a909def69414bbd60cdfdac9ad807"| OffBarCapping/Rule_Off_Bar_Tariff_Capping_16_6b6f1282708449448fc434e820fa8e1f# at OffBarCapping.Rule_Off_Bar_Tariff_Capping_16_6b6f1282708449448fc434e820fa8e1fPredicate0InvokerGenerated.evaluate(Unknown Source)# at OffBarCapping.Rule_Off_Bar_Tariff_Capping_16_6b6f1282708449448fc434e820fa8e1fPredicate0Invoker.evaluate(Unknown Source)# at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:299)# 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:294)# 1. Some surfing on the internet referred us to a similar JIRA issue:- JBRULES-3675<https://issues.jboss.org/browse/JBRULES-3675> It says this has been fixed in 6.0.0. We were not in a position to upgrade to 6.0.0 right away and hence decide to apply a patch in drools-core-5.4.0.Final.jar Drools: 5.4.0 public Class<?> More ...fastFindClass( final String name ) { Class<?> cls = findLoadedClass( name ); if (cls == null) { final byte[] clazzBytes = this.store.read( convertClassToResourcePath( name ) ); if (clazzBytes != null) { String pkgName = name.substring( 0, name.lastIndexOf( '.' ) ); if (getPackage( pkgName ) == null) { definePackage( pkgName, "", "", "", "", "", "", null ); } cls = defineClass( name, clazzBytes, 0, clazzBytes.length, PROTECTION_DOMAIN ); } if (cls != null) { resolveClass( cls ); } } return cls; } Path applied:- public Class fastFindClass(String name) { Class cls = findLoadedClass(name); if(cls == null) { byte clazzBytes[] = store.read(JavaDialectRuntimeData.convertClassToResourcePath(name)); if(clazzBytes != null) { String pkgName = name.substring(0, name.lastIndexOf('.')); if(!existingPackages.contains(pkgName)) { synchronized(this) { if(!existingPackages.contains(pkgName)) { if(getPackage(pkgName) == null) { definePackage(pkgName, "", "", "", "", "", "", null); } existingPackages.add(pkgName); } } } cls = defineClass(name, clazzBytes, 0, clazzBytes.length, JavaDialectRuntimeData.access$000()); } if(cls != null) { resolveClass(cls); } } return cls; } But we are still getting this Error. Let me know if any one did face a similar issue and solution for the same. Thanks and regards, Karan Malhotra The contents of this email, including the attachments, are PRIVILEGED AND CONFIDENTIAL to the intended recipient at the email address to which it has been addressed. If you receive it in error, please notify the sender immediately by return email and then permanently delete it from your system. The unauthorized use, distribution, copying or alteration of this email, including the attachments, is strictly forbidden. Please note that neither MakeMyTrip nor the sender accepts any responsibility for viruses and it is your responsibility to scan the email and attachments (if any). No contracts may be concluded on behalf of MakeMyTrip by means of email communications. _______________________________________________ rules-users mailing list rules-users@lists.jboss.org<mailto:rules-users@lists.jboss.org> https://lists.jboss.org/mailman/listinfo/rules-users The contents of this email, including the attachments, are PRIVILEGED AND CONFIDENTIAL to the intended recipient at the email address to which it has been addressed. If you receive it in error, please notify the sender immediately by return email and then permanently delete it from your system. The unauthorized use, distribution, copying or alteration of this email, including the attachments, is strictly forbidden. Please note that neither MakeMyTrip nor the sender accepts any responsibility for viruses and it is your responsibility to scan the email and attachments (if any). No contracts may be concluded on behalf of MakeMyTrip by means of email communications.

No changes in 5.6.0 in org.drools.rule.JavaDialectRuntimeData$PackageClassLoader.fastFindClass(String name). And as per the Jira issue, fix version is 6.0.0 -- View this message in context: http://drools.46999.n3.nabble.com/rules-users-Linkage-Error-In-execute-me... Sent from the Drools: User forum mailing list archive at Nabble.com.