[rules-users] Multithreading work items

Mon Apr 26 10:53:57 EDT 2010

it's not a problem really..

2010/4/26 Pedro Maria Buitrago Mantilla <pmbtgun at gmail.com>

>
> The problem is the multithreading execution. For a "SPLIT NODE" of type
> "AND", first, is process one branch, after, the next branch and so on for
> each. The execution is sequential.
>
> PEDRO MARIA BUITRAGO MANTILLA
> Bogotá, Colombia
>
>
>
> 2010/4/26 rudolf michael <roudolf at gmail.com>
>
> Alan, couldn't you have achieved this using a Split and Join?
>>
>> 2010/4/26 <Alan.Gairey at tessella.com>
>>
>>
>>> Interesting. What you've described Pedro is similar to what I'm trying to
>>> achieve, and also relates to some earlier posts I made to the list (title:
>>> 'Drools Flow: Problem with constraint in (Wait) State node').
>>>
>>> I have a process that launches independent sub flows; these independent
>>> sub flows execute on separate threads. I then want the original process to
>>> "block" until all the subflows have finished, and to then continue.
>>> In order to achieve this, I've done the following:
>>>
>>> - Each process (both the main flow and each sub flow) is executed by a
>>> separate stateful knowledge session.
>>> - When a sub flow is started, it inserts a fact into the working memory
>>> of the session for the original process.
>>> - When a sub flow finishes, it updates a fact in the working memory of
>>> the session for the original process to "signal" its completion.
>>> - After launching the sub flows, the original process contains a (wait)
>>> state node; the constraint for this node is designed to block until all
>>> facts in its memory are in the "signalled" state.
>>>
>>> I've attached an example project that illustrates what I'm trying to
>>> achieve. The constraint on the wait state node is currently as follows:
>>>
>>> (and forall(SimpleFact(complete == true)) exists(SimpleFact()))
>>>
>>> I'd be interested to know from someone who understands rule syntax better
>>> than me as to why this seems to work when other attempts (see my earlier
>>> posts) failed.
>>>
>>> I still have two problems though:
>>>
>>> 1) The above constraint appeared to work OK with an earlier 5.1 snapshot
>>> build (from a couple of months back). However, using the latest successful
>>> build from trunk (#3845), the Action node after the wait state node isn't
>>> executed. Given that 5.1.M2 is supposed to be imminent, I'm worried. Does
>>> anyone know why this no longer works?
>>>
>>> 2) If I try to enable JPA-based state persistence, using the Bitronix
>>> transaction manager, then when I try to insert a fact into the  working
>>> memory of the session for the original process from a separate thread, I get
>>> the following error:
>>>
>>> bitronix.tm.internal.BitronixRollbackException: transaction was marked as
>>> rollback only and has been rolled back
>>>         at
>>> bitronix.tm.BitronixTransaction.commit(BitronixTransaction.java:153)
>>>         at
>>> bitronix.tm.BitronixTransactionManager.commit(BitronixTransactionManager.java:96)
>>>         at
>>> org.drools.persistence.session.SingleSessionCommandService.execute(SingleSessionCommandService.java:258)
>>>         at
>>> org.drools.command.impl.CommandBasedStatefulKnowledgeSession.insert(CommandBasedStatefulKnowledgeSession.java:306)
>>>         at
>>> com.test.InsertWorkItemHandler$1.insertFact(InsertWorkItemHandler.java:52)
>>>         at
>>> com.test.InsertWorkItemHandler$1.run(InsertWorkItemHandler.java:40)
>>>         at java.lang.Thread.run(Thread.java:619)
>>> java.lang.RuntimeException: Could not rollback transaction
>>>         at
>>> org.drools.persistence.session.SingleSessionCommandService.execute(SingleSessionCommandService.java:283)
>>>         at
>>> org.drools.command.impl.CommandBasedStatefulKnowledgeSession.insert(CommandBasedStatefulKnowledgeSession.java:306)
>>>         at
>>> com.test.InsertWorkItemHandler$1.insertFact(InsertWorkItemHandler.java:52)
>>>         at
>>> com.test.InsertWorkItemHandler$1.run(InsertWorkItemHandler.java:40)
>>>         at java.lang.Thread.run(Thread.java:619)
>>> Caused by: java.lang.IllegalStateException: no transaction started on
>>> this thread
>>>         at
>>> bitronix.tm.BitronixTransactionManager.rollback(BitronixTransactionManager.java:103)
>>>         at
>>> org.drools.persistence.session.SingleSessionCommandService.execute(SingleSessionCommandService.java:278)
>>>         ... 4 more
>>>
>>> Any help anyone can provide would be very much appreciated. Thank you.
>>>
>>> Regards,
>>>
>>> Alan
>>>
>>>
>>>
>>>
>>>  *Pedro Maria Buitrago Mantilla <pmbtgun at gmail.com>*
>>> Sent by: rules-users-bounces at lists.jboss.org
>>>
>>> 23/04/2010 14:38
>>>  Please respond to
>>> Rules Users List <rules-users at lists.jboss.org>
>>>
>>>   To
>>> Rules Users List <rules-users at lists.jboss.org>
>>> cc
>>>   Subject
>>> Re: [rules-users] Multithreading work items
>>>
>>>
>>>
>>>
>>> Each of the sub flows requires final user design. Mauricio thanks very
>>> much.
>>>
>>> PEDRO BUITRAGO
>>> Bogotá, Colombia
>>>
>>>
>>> 2010/4/22 Mauricio Salatino <*salaboy at gmail.com* <salaboy at gmail.com>>
>>> yes.. sounds more like a normal java problem than Drools FLow problem. I
>>> think that your solution is the correct one because it handle internally the
>>> multithreaded requierements and then it continue the business process
>>> normally.
>>>
>>>
>>> 2010/4/22 Pedro Maria Buitrago Mantilla <*pmbtgun at gmail.com*<pmbtgun at gmail.com>>
>>>
>>>
>>> The idea is to run multiple independent sub flows. Each of the sub flows
>>> requires approximately 2 minutes to complete, so parallel processing is
>>> required. Once all the sub flows have completed their tasks is necessary to
>>> collect all the results and process them. This implies that the workflow
>>> should not end until it collects all information submitted by the sub flows.
>>>
>>> For now, I think to create, with JMS, a queue in jboss receive the name
>>> of each sub flow, create your own KnowledgeBase run each subflow as a
>>> separate workflow and delivers the results. Finally, some components will
>>> take all the results (from a database of another jms queue and process and
>>> again another component start another workflow to process all results.
>>>
>>>
>>> PEDRO BUITRAGO
>>> Bogotá, Colombia
>>>
>>>
>>> 2010/4/22 Mauricio Salatino <*salaboy at gmail.com* <salaboy at gmail.com>>
>>>
>>> can you describe a little bit your use case?
>>> I'm not sure about what you want to achieve.
>>>
>>> 2010/4/21 Pedro Maria Buitrago Mantilla <*pmbtgun at gmail.com*<pmbtgun at gmail.com>
>>> >
>>> In general, I meet that for resolve the topic of multithreading it's
>>> required to implement another thread over a work item.
>>>
>>> How does the asynchronic task  can modified a variable of Knowledgebase?
>>>
>>> Can you give me an example?
>>>
>>> Pedro Buitrago
>>>
>>>
>>>
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>>
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- Salatino "Salaboy" Mauricio -
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