[rules-users] java.lang.ClassCastException: org.drools.reteoo.BetaMemory cannot be cast to org.drools.reteoo.AlphaNode$AlphaMemory

[dcrissman]

While working on a sanitized version of the code, I discovered my issue. 

I am using a StatefulKnowledgeSession essentially statelessly. I am doing
this because in the past I have found StatefulKnowledgeSession to be more
feature rich. Regardless, each execution created a new
StatelessKnowledgeSession instance which is built from a single instance of
a KnowledgeBase. During the setup for each run, I was adding my change_set
to that KnowledgeBase, causing the error I was getting. I'd like to think
that my mistake could be recycled and benefit someone else in the future.

Davide - Thank you for your time. Sorry that this turned out to be user
error.

-Dennis 


Davide Sottara wrote
> Could you post **at least** the unit test throwing the exception,
> the one that "enables" it and the code you are using to run them?
> This may be yet another blocker for 5.6, so I'd like to investigate it
> as soon as possible
> Thanks!
> Davide
> 
> On 05/02/2013 07:20 AM, dcrissman wrote:
>> Yes, I am getting this exception (sadly, not something that I am just
>> worried
>> about).
>>
>> I am checking for rule complication errors before running the rules, and
>> no
>> errors are being given.
>>
>> I am not dynamically adding or removing rules once I have my knowledge
>> base
>> setup, it does not change though the duration of the run.
>>
>> I am using a StatefulKnowledgeSession, and I make sure that after each
>> run
>> that I am calling dispose in a finally block. So shouldn't be any strange
>> memory issues.
>>
>> To add to the original description, I am getting these exceptions in my
>> unit
>> tests. There is one unit test suite that when disabled the exception goes
>> away, but when enabled the exceptions happen in other suites. Which of
>> course is odd and led me to believe that there is a problem with the unit
>> tests (which is still not ruled out). But the suites are using different
>> sessions, same rules, but totally different instances of everything.
>>
>> The only thing I am doing that may be a little funny is consolidating a
>> collection of objects into one then retracting the collection, but when I
>> comment out this rule I still am getting this exception. Aside from this
>> one
>> case, I am not doing anything crazy.
>>
>> [code]
>> //ArrayList provided by drools seems to dynamically adjust with the
>> retractions, this safeguards us against that.
>> ArrayList safetyArr = new ArrayList($attrs);
>>
>> ArrayList values = new ArrayList();
>> for (int i=0; i < safetyArr.size(); i++){
>> 	Attribute attr = ((Attribute) safetyArr.get(i));
>> 	values.add(attr.getValue());
>> 	retract(attr);
>> }
>>
>> insert(newAttribute($redHatName, StringUtils.join(values, ",")));
>> [/code]
>>
>> Any other thoughts you may have would be appreciated.
>>
>> Thanks!
>>
>>
>> Davide Sottara wrote
>>> The original thread was for a bug in 5.0.x, fixed in 5.1, but it would
>>> be
>>> a
>>> very serious issue in 5.5. It basically means that the local memory of a
>>> beta node has been assigned to an alpha node, or that the wrong memory
>>> had
>>> been retrieved. In any case, the rete is broken: wrong facts or types
>>> would
>>> be joined in a different order or way than stated by the rules.
>>>
>>> Is this something you're experiencing , or just worried that it may
>>> happen?
>>>
>>> Causes could be an invalid rule in the first place (running the engine
>>> without checking for compilation errors), a bug in the construction
>>> process
>>> (unlikely, unless the rule is a very rare edge case), or a complex
>>> scenario
>>> where you add and remove rules dynamically from a knowledge base.
>>> On May 1, 2013 2:25 PM, "dcrissman" &lt;
>>> dcrissman@
>>> &gt; wrote:
>>>
>>>> Could you explain what you mean by rete corruption? I am familiar with
>>>> rete,
>>>> but hardly an expert. I am not really doing anything too complicated, I
>>>> guess some runtime inserts and retracts.
>>>>
>>>> I tried 6.0.0.Beta2, but that has more api changes then I am prepared
>>>> to
>>>> handle, I'll wait until the Final version.
>>>>
>>>> As for 5.6.0-SNAPSHOT, I am having trouble pulling it down. I will pick
>>>> that
>>>> up tomorrow.
>>>>
>>>> In the meantime, any clarification to the rete question would be
>>>> appreciated.
>>>>
>>>> Thanks,
>>>> Dennis
>>>>
>>>>
>>>>
>>>> --
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>>
>>
>>
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