[rules-users] threw error java.lang.ClassCastException: org.drools.reteoo.FromNode$FromMemory cannot be cast to org.drools.reteoo.BetaMemory

[Davide Sottara]

Ok, so there are two main possibilities.. either the locking mechanism
does not work appropriately
and there is a concurrency issue,  or the particular rule structure
exposes an edge case in node
comparison and reuse.
The former is more probable, but should be relatively easy to see. I
need your help in testing this
in the production environment where you get the exception.

You should essentially add a
org.drools.event.knowledgebase.KnowledgeBaseEventListener to the
knowledge base :

kb.addEventListener(  new MyLoggingKBEventListener() );

and provide an implementation that suitably logs which thread is
executing which action.
The KnowledgeBaseEventListener is an interface with methods such as:

 void beforeKnowledgeBaseLocked(BeforeKnowledgeBaseLockedEvent event);
 void afterKnowledgeBaseLocked(AfterKnowledgeBaseLockedEvent event);
 void beforeRuleAdded(BeforeRuleAddedEvent event);
 void afterRuleAdded(AfterRuleAddedEvent event);

etc...

Can you try this solution?
Thanks!
Davide


On 05/08/2013 10:57 AM, mohdejaz74 wrote:
> I use KB methods directly
>
> For adding/updating a rule, I create a temporary instance of
> KnowledgeBuilder and add the rule to check if there are any errors.
>
> If there are no errors, I first remove (if rule needs to be updated) the
> previous rule by calling this ...
>
> kb.removeRule(ro.pkg, ro.name);
>
> Then I add the new rule ...
>
> kb.addKnowledgePackages(kbuilder.getKnowledgePackages());
>
> Ejaz
>
>
>
>
> --
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