[rules-users] AfterEvaluatorDefinition NullPointer Exception in deserialized ksession
[Drools 5.5.0 Final] I wrote a webserver that keeps StatefulKnowledgeSessions running in Stream mode. When the server is stopped, the sessions are serialized and stored in a database. When the server is restarted, the existing sessions are restored / deserialized. Some time after recreating the session and inserting some events I get the following exception: java.lang.NullPointerException: null at org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:351) ... Apparently the exception seems to be related to a rule that uses temporal reasoning. After getting it once, the session seems to be corrupt - from now on every time I call ksession.insert(event) the same exception occurs. When I serialize the session and attempt to deserialize it, I get a long stack trace -- I can not deserialize it anymore. (as apparently it is corrupted). When I run the server with the same events/sessions without stopping (serialization/deserialization) the exception does not occur) Can I do anything to prevent this behaviour? I thought maybe the after timer/trigger is somehow still active when I serialize the ksession. I tried ksession.halt() before serialization, but with no effect. Any ideas? signature.asc Description: Message signed with OpenPGP using GPGMail ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] AfterEvaluatorDefinition NullPointer Exception in deserialized ksession
Hey Alexander, Would this be related to this? https://issues.jboss.org/browse/DROOLS-243 If it is this one, you can do something like this as a workaround before constructing the KBase: Operator op = BeforeEvaluatorDefinition.BEFORE; Operator op = AfterEvaluatorDefinition.AFTER; This will cause the evaluation definition to be put in memory. Hope this helps! Demian On Fri, Oct 11, 2013 at 9:21 AM, Alexander Wolf m...@alexander-wolf.netwrote: [Drools 5.5.0 Final] I wrote a webserver that keeps StatefulKnowledgeSessions running in Stream mode. When the server is stopped, the sessions are serialized and stored in a database. When the server is restarted, the existing sessions are restored / deserialized. Some time after recreating the session and inserting some events I get the following exception: java.lang.NullPointerException: null at org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:351) ... Apparently the exception seems to be related to a rule that uses temporal reasoning. After getting it once, the session seems to be corrupt - from now on every time I call ksession.insert(event) the same exception occurs. When I serialize the session and attempt to deserialize it, I get a long stack trace -- I can not deserialize it anymore. (as apparently it is corrupted). When I run the server with the same events/sessions without stopping (serialization/deserialization) the exception does not occur) Can I do anything to prevent this behaviour? I thought maybe the after timer/trigger is somehow still active when I serialize the ksession. I tried ksession.halt() before serialization, but with no effect. Any ideas? ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] AfterEvaluatorDefinition NullPointer Exception in deserialized ksession
Hey Demian, thank you! This might actually be related. But how do I get the reference to these Operators to (re)set them? This is my unmarshalling code (pretty simple and basic..): ByteArrayInputStream bais = new ByteArrayInputStream(serializedKnowledgeBase); ObjectInputStream ois = new ObjectInputStream(bais); kbase = (KnowledgeBase)ois.readObject(); Marshaller marshaller = MarshallerFactory.newMarshaller(kbase); ByteArrayInputStream bais2 = new ByteArrayInputStream(serializedKnowledgeSession); knowledgeSession = marshaller.unmarshall(bais2); Also: Is this going to be fixed in 5.6.0 ? (@Mark Proctor?) - Alex On 11.10.2013, at 16:09, Demian Calcaprina calcacue...@gmail.com wrote: Hey Alexander, Would this be related to this? https://issues.jboss.org/browse/DROOLS-243 If it is this one, you can do something like this as a workaround before constructing the KBase: Operator op = BeforeEvaluatorDefinition.BEFORE; Operator op = AfterEvaluatorDefinition.AFTER; This will cause the evaluation definition to be put in memory. Hope this helps! Demian On Fri, Oct 11, 2013 at 9:21 AM, Alexander Wolf m...@alexander-wolf.net wrote: [Drools 5.5.0 Final] I wrote a webserver that keeps StatefulKnowledgeSessions running in Stream mode. When the server is stopped, the sessions are serialized and stored in a database. When the server is restarted, the existing sessions are restored / deserialized. Some time after recreating the session and inserting some events I get the following exception: java.lang.NullPointerException: null at org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:351) ... Apparently the exception seems to be related to a rule that uses temporal reasoning. After getting it once, the session seems to be corrupt - from now on every time I call ksession.insert(event) the same exception occurs. When I serialize the session and attempt to deserialize it, I get a long stack trace -- I can not deserialize it anymore. (as apparently it is corrupted). When I run the server with the same events/sessions without stopping (serialization/deserialization) the exception does not occur) Can I do anything to prevent this behaviour? I thought maybe the after timer/trigger is somehow still active when I serialize the ksession. I tried ksession.halt() before serialization, but with no effect. Any ideas? ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users signature.asc Description: Message signed with OpenPGP using GPGMail ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] AfterEvaluatorDefinition NullPointer Exception in deserialized ksession
Yes.. but you can include these two lines before this, to check. Operator op = BeforeEvaluatorDefinition.BEFORE; Operator op = AfterEvaluatorDefinition.AFTER; The problem in that, for example, for the before, https://github.com/droolsjbpm/drools/blob/5.5.x/drools-core/src/main/java/org/drools/base/evaluators/BeforeEvaluatorDefinition.java#L82 If you don-t mention not use this class before trying to unmarshall it, the operator is not added to the operators registry, and thus NPE is thrown. public static final Operator BEFORE= Operator.addOperatorToRegistry( before, false ); In the ticket I included a patch to fix it, I have one thing pending to add to the pull request in order to be ready to be merged. But the workaround of just mentioning the evaluator definitions so they are added to the operators list, before doing the unmarshall, has worked for me. Thanks, Demian Demian On Fri, Oct 11, 2013 at 12:09 PM, Alexander Wolf m...@alexander-wolf.netwrote: Hey Demian, thank you! This might actually be related. But how do I get the reference to these Operators to (re)set them? This is my unmarshalling code (pretty simple and basic..): ByteArrayInputStream bais = new ByteArrayInputStream( serializedKnowledgeBase); ObjectInputStream ois = new ObjectInputStream(bais); kbase = (KnowledgeBase)ois.readObject(); Marshaller marshaller = MarshallerFactory.newMarshaller(kbase); ByteArrayInputStream bais2 = new ByteArrayInputStream( serializedKnowledgeSession); knowledgeSession = marshaller.unmarshall(bais2); Also: Is this going to be fixed in 5.6.0 ? (@Mark Proctor?) - Alex On 11.10.2013, at 16:09, Demian Calcaprina calcacue...@gmail.com wrote: Hey Alexander, Would this be related to this? https://issues.jboss.org/browse/DROOLS-243 If it is this one, you can do something like this as a workaround before constructing the KBase: Operator op = BeforeEvaluatorDefinition.BEFORE; Operator op = AfterEvaluatorDefinition.AFTER; This will cause the evaluation definition to be put in memory. Hope this helps! Demian On Fri, Oct 11, 2013 at 9:21 AM, Alexander Wolf m...@alexander-wolf.netwrote: [Drools 5.5.0 Final] I wrote a webserver that keeps StatefulKnowledgeSessions running in Stream mode. When the server is stopped, the sessions are serialized and stored in a database. When the server is restarted, the existing sessions are restored / deserialized. Some time after recreating the session and inserting some events I get the following exception: java.lang.NullPointerException: null at org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:351) ... Apparently the exception seems to be related to a rule that uses temporal reasoning. After getting it once, the session seems to be corrupt - from now on every time I call ksession.insert(event) the same exception occurs. When I serialize the session and attempt to deserialize it, I get a long stack trace -- I can not deserialize it anymore. (as apparently it is corrupted). When I run the server with the same events/sessions without stopping (serialization/deserialization) the exception does not occur) Can I do anything to prevent this behaviour? I thought maybe the after timer/trigger is somehow still active when I serialize the ksession. I tried ksession.halt() before serialization, but with no effect. Any ideas? ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
