[rules-users] java.lang.NoClassDefFoundError in rule execution

Hi, folks, I'm using Drools 5.1, JDK 1.6 on tomcat 6.0.28 to build a OLTP application. System's volume is about 1.5 million transactions a day. The pilot PROD release was done about 1 week ago and we've noticed many NoClassDefFoundError exception run time. A sample piece is pasted below. For information security concern, I masked class names here. This happened much more frequent when system load pressure is big - memory is between 80% to 100% and disk is between 80% - 100%. As we are running on a cloud virtual instance environment, virtual node has relatively small profile - 40GB disk, 4GB memory, 2 core Intel 3.0 GHz CPU. I've searched through the web and found some reported bug - https://issues.jboss.org/browse/JBRULES-2253?_sscc=t. here I got two questions: 1. If anybody in the community has met similar issue before and how you fix it? 2. It seems I can either convert my rule into Java Dialect or turn off MVEL2 JIT attribute: Dmvel2.disable.jit=true. Does anybody have summary information about the good and bad between MVEL and JAVA dialect? ERROR>2012-03-09 10:00:22,432 com.xxx.xxx.xxx.drools.SessionManager[pool-5-thread-6]: Unexpected error : java.lang.NoClassDefFoundError: com/xxx/xxx/xxx/xxx/xxx/GetAmountTolerance at ASMAccessorImpl_20916505061331280591040.getValue(Unknown Source) at org.mvel2.optimizers.dynamic.DynamicGetAccessor.getValue(DynamicGetAccessor. java:73) at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:110) at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.jav a:124) at org.mvel2.MVELRuntime.execute(MVELRuntime.java:89) at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:125) at org.mvel2.MVEL.executeExpression(MVEL.java:928) at org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpressio n.java:101) at org.drools.rule.PredicateConstraint.isAllowedCachedLeft(PredicateConstraint. java:314) at org.drools.common.DefaultBetaConstraints.isAllowedCachedLeft(DefaultBetaCons traints.java:226) at org.drools.reteoo.JoinNode.assertLeftTuple(JoinNode.java:98) at org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(Sing leLeftTupleSinkAdapter.java:197) at org.drools.reteoo.SingleLeftTupleSinkAdapter.createAndPropagateAssertLeftTup le(SingleLeftTupleSinkAdapter.java:146) at org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.jav a:154) at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObject SinkAdapter.java:59) at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:134) at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObject SinkAdapter.java:59) at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:134) at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(Composi teObjectSinkAdapter.java:450) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(Composite ObjectSinkAdapter.java:368) at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:193) at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:191) at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:332) at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:293) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:90 5) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:86 4) at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSession Impl.java:255) at com.ssc.gce.reconcile.drools.SessionManager.insert(SessionManager.java:116) at com.ssc.gce.reconcile.drools.SessionManager.run(SessionManager.java:171) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.ja va:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:9 08) at java.lang.Thread.run(Thread.java:662)