[rules-users] Why StatelessKnowledgeSession Instantiates a New StatefulKnowledgeSession on Each execute()?

[Wolfgang Laun]

Not just activations. The famous Tokens of Rete referring to facts matching
this or that pattern constraint are all over this network.
-W

2011/1/30 yj h <hyjshanghai at gmail.com>

> I see. Thank you.
> For instance, retracting a fact with lots of pending activations associated
> with this fact could me expensive. Am I right?
>
> 2011/1/27 Esteban Aliverti <esteban.aliverti at gmail.com>
>
>> Sessions are cheap to create.
>> The problem of removing all the facts and then insert new ones is that
>> depending on you rules, could be much more expensive than throw the old
>> session and create a new one. And you should also think about globals as
>> well. Removing a Fact is not just taking it off from a list. There is a lot
>> of logic involved there.
>> Is like if you have a populated List and you want to remove all its items
>> and fill it with new ones (from another List for example).
>> What would you use?
>>
>> originalList.clear();
>> originalList.addAll(anotherList);
>>
>> or
>>
>> originalList = new ArrayList(anotherList);
>>
>> Best Regards,
>>
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>>
>> Esteban Aliverti
>> - Developer @ http://www.plugtree.com
>> - Blog @ http://ilesteban.wordpress.com
>>
>>
>>
>> On Thu, Jan 27, 2011 at 5:45 AM, hyjshanghai <hyjshanghai at gmail.com>wrote:
>>
>>>
>>> According to Section 3.3.7 "StatelessKnowledgeSession" of
>>>
>>> http://downloads.jboss.com/drools/docs/5.1.1.34858.FINAL/drools-expert/html/ch03.html#d0e1956
>>> the Drools document , "the act of calling execute() is a single-shot
>>> method
>>> that will internally instantiate a StatefulKnowledgeSession".
>>>
>>> Why StatelessKnowledgeSession instantiates a new statefulKnowledgeSession
>>> object on Each execute()?
>>>
>>> Instead, can it be implemented as inserting the fact into an existing
>>> empty
>>> statefulKnowledgeSession, and retract the fact after
>>> statefulKnowledgeSession.fireAllRules()?
>>>
>>> I think the current implementation will cause StatelessKnowledgeSession
>>>  to
>>> be slower than statefulKnowledgeSession, as opposed to "common sense"
>>> that
>>> the former is less complex and should be faster. Any performance
>>> benchmark
>>> on Stateless v.s. Stateful Sessions?
>>> --
>>> View this message in context:
>>> http://drools-java-rules-engine.46999.n3.nabble.com/Why-StatelessKnowledgeSession-Instantiates-a-New-StatefulKnowledgeSession-on-Each-execute-tp2360846p2360846.html
>>> Sent from the Drools - User mailing list archive at Nabble.com.
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>>> rules-users mailing list
>>> rules-users at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>
>>
>>
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>>
>
>
> --
> Best Wishes,
> Huang, Yijian
>
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