[rules-dev] ConcurrentModificationException thrown from EntryPointNode.updateSink

[Tom.E.Murphy at wellsfargo.com]

Using Drools 5.0.1 FINAL

Our logs contain the following exception:

java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:2117)
        at java.util.HashMap$ValueIterator.next(HashMap.java:2147)
        at org.drools.reteoo.EntryPointNode.updateSink(EntryPointNode.java:285)
        at org.drools.reteoo.ObjectTypeNode.attach(ObjectTypeNode.java:279)
        at org.drools.reteoo.builder.PatternBuilder.attachObjectTypeNode(PatternBuilder.java:234)
        at org.drools.reteoo.ClassObjectTypeConf.<init>(ClassObjectTypeConf.java:93)
        at org.drools.common.ObjectTypeConfigurationRegistry.getObjectTypeConf(ObjectTypeConfigurationRegistry.java:58)
        at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:849)
        at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:788)
        at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:216)
        at com.wellsfargo.ARGenT.Execution.SimXmlDataLoader.Load(SimXmlDataLoader.java:713)



The code fragment around line 285 of EntryPointNode.java is the following:
Could the nested call to assertObject be causing the ConcurrentModificationException?
In other words, could the call to sink.assertObject cause an eventual recursive entry into updateSink or call another method that changes the registry and effectively invalidates the objectTypeConf iterator?



    public void updateSink(final ObjectSink sink,
                           final PropagationContext context,
                           final InternalWorkingMemory workingMemory) {
        // @todo
        // JBRULES-612: the cache MUST be invalidated when a new node type is added to the network, so iterate and reset all caches.
        final ObjectTypeNode node = (ObjectTypeNode) sink;

        final ObjectType newObjectType = node.getObjectType();

   InternalWorkingMemoryEntryPoint wmEntryPoint = (InternalWorkingMemoryEntryPoint) workingMemory.getWorkingMemoryEntryPoint( this.entryPoint.getEntryPointId() );

LINE 285: for ( ObjectTypeConf objectTypeConf : wmEntryPoint.getObjectTypeConfigurationRegistry().values() ) {
            if ( newObjectType.isAssignableFrom( objectTypeConf.getConcreteObjectTypeNode().getObjectType() ) ) {
                objectTypeConf.resetCache();
                ObjectTypeNode sourceNode = objectTypeConf.getConcreteObjectTypeNode();
                Iterator it = ((ObjectHashSet) workingMemory.getNodeMemory( sourceNode )).iterator();
                for ( ObjectEntry entry = (ObjectEntry) it.next(); entry != null; entry = (ObjectEntry) it.next() ) {
                    sink.assertObject( (InternalFactHandle) entry.getValue(),
                                       context,
                                       workingMemory );
                }
            }
        }
    }

Tom Murphy
Business Process Consultant
Wells Fargo HCFG - CORE Deal Decisioning Platform
800 S. Jordan Creek Parkway | West Des Moines, IA 50266
MAC: X2301-01B
Office: 515 324 4853 | Mobile: 941 320 8014
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