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

Mon May 6 14:33:43 EDT 2013

Sorry, but I doubt that anyone can benefit from this somewhat
obscure description of a use case - but thanks for trying.
-W

On 06/05/2013, dcrissman <dcrissman at redhat.com> wrote:
> 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
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> View this message in context:
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