[rules-users] Help debugging NPE
Edson Tirelli
tirelli at post.com
Wed Jun 24 18:43:48 EDT 2009
Dirk
Drools 5 is mostly backward compatible with Drools 4. You don't need to
migrate to the new API, although it is recommended.
Anyway, I understand your concern. My wild wild guess is that the
memberOf operator is complaining about a null in that constraint. If that is
the case, it is a bug. I fixed some bugs like that in Drools 5 trunk:
https://jira.jboss.org/jira/browse/JBRULES-2102
[]s
Edson
2009/6/24 Dirk Bergstrom <dirk at juniper.net>
> Edson Tirelli was heard to exclaim, On 06/24/09 06:14:
> > The problem seems not related to shadow facts, but to constraint
> > resolution and fact data extraction. It might be a bug or not... need
> > more info.
>
> I've also seen the following stacktrace:
>
> java.lang.ArrayIndexOutOfBoundsException: 40440
> at
> org.drools.util.TupleIndexHashTable.toArray(TupleIndexHashTable.java:217)
> at org.drools.reteoo.CollectNode.retractObject(CollectNode.java:260)
> at
>
> org.drools.reteoo.SingleObjectSinkAdapter.propagateRetractObject(SingleObjectSinkAdapter.java:32)
> at org.drools.reteoo.AlphaNode.retractObject(AlphaNode.java:164)
> at
>
> org.drools.reteoo.SingleObjectSinkAdapter.propagateRetractObject(SingleObjectSinkAdapter.java:32)
> at org.drools.reteoo.AlphaNode.retractObject(AlphaNode.java:164)
> at
>
> org.drools.reteoo.CompositeObjectSinkAdapter.propagateRetractObject(CompositeObjectSinkAdapter.java:366)
> at
> org.drools.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java:189)
> at org.drools.reteoo.Rete.retractObject(Rete.java:215)
> at
> org.drools.reteoo.ReteooRuleBase.retractObject(ReteooRuleBase.java:211)
> at
>
> org.drools.reteoo.ReteooWorkingMemory.doRetract(ReteooWorkingMemory.java:79)
> at
>
> org.drools.common.AbstractWorkingMemory.retract(AbstractWorkingMemory.java:1023)
> at
>
> org.drools.common.AbstractWorkingMemory.retract(AbstractWorkingMemory.java:982)
> at
>
> net.juniper.dash.data.DataSource.reconcileAssertedRecords(DataSource.java:362)
>
> > In any case, the offending rule is not the one you showed. The
> > offending rule contains a double beta constraint in a join:
>
> I know it's not in that rule. It must be in this one, since it's the only
> one
> that uses rli_nums:
>
> $npi : NPIRecord( )
> $pr : PRRecord( npi == "", rli != "" )
> $rli : RLIRecord( id memberOf $pr.rli_nums, npi_program == $npi.synopsis )
>
> > Can you narrow it down? Did you tried with Drools 5.0.1?
>
> I haven't tried any of the 5.x series. Is there a guide to migrating my
> code
> from 4.0 to 5.0? I looked on the jboss site, the wiki, the blog, and this
> mailing list, but I didn't find anything. I'm under a lot of time
> pressure, and
> changing to 5.0 doesn't look like a quick fix...
>
> > 2009/6/24 Dirk Bergstrom <dirk at juniper.net <mailto:dirk at juniper.net>>
> >
> > I'm running into an NPE using Drools 4.0.7, and I'm stumped by it
> > (stacktrace
> > below). I made some changes to seemingly unrelated code, and this
> > error started
> > showing up. It would help me to understand what's going on if
> > someone could
> > tell me roughly what's going on here. Since the error is thrown by
> > generated
> > code (in what I assume is a shadow proxy), I can't tell what the
> > offending null
> > pointer is. I'm not even entirely sure what's triggering the bug
> > (it happens
> > half an hour into the run of big multi-threaded application with
> > about 40K
> > objects in the working memory).
> >
> > Is this happening because:
> >
> > *) getRli_nums() in one of my PRRecord objects is returning a null
> > value?
> >
> > *) There is a null PRRecord object backing the shadow proxy?
> >
> > *) Some other thing is null?
> >
> > *) I'm running into a bug in Drools?
> >
> > I stuck in this rule:
> >
> > when
> > $pr : PRRecord( rli_nums == null )
> > then
> > System.out.println($pr.getId());
> > end
> >
> > And it didn't print anything, so I'm inclined to think that this is
> > not a simple
> > matter of something returning a null value...
> >
> > I'll be most appreciative of any help I can get.
> >
> > Here's the stacktrace:
> >
> > java.lang.NullPointerException
> > at
> >
> org.drools.base.net.juniper.dash.data.PRRecord13409648$getRli_nums.getValue(Unknown
> > Source)
> > at
> >
> org.drools.base.ClassFieldExtractor.getValue(ClassFieldExtractor.java:127)
> > at
> >
> org.drools.base.evaluators.BaseMemberOfEvaluator.evaluateCachedRight(BaseMemberOfEvaluator.java:45)
> > at
> >
> org.drools.rule.VariableRestriction.isAllowedCachedRight(VariableRestriction.java:89)
> > at
> >
> org.drools.rule.VariableConstraint.isAllowedCachedRight(VariableConstraint.java:81)
> > at
> >
> org.drools.common.DoubleBetaConstraints.isAllowedCachedRight(DoubleBetaConstraints.java:164)
> > at org.drools.reteoo.JoinNode.retractObject(JoinNode.java:189)
> > at
> >
> org.drools.reteoo.CompositeObjectSinkAdapter.propagateRetractObject(CompositeObjectSinkAdapter.java:375)
> > at
> >
> org.drools.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java:189)
> > at org.drools.reteoo.Rete.retractObject(Rete.java:215)
> > at
> >
> org.drools.reteoo.ReteooRuleBase.retractObject(ReteooRuleBase.java:211)
> > at
> >
> org.drools.reteoo.ReteooWorkingMemory.doRetract(ReteooWorkingMemory.java:79)
> > at
> >
> org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:1250)
> > at
> >
> org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:1203)
> > at
> >
> net.juniper.dash.data.DataSource.reconcileAssertedRecords(DataSource.java:409)
>
>
> --
> Dirk Bergstrom dirk at juniper.net
> _____________________________________________
> Juniper Networks Inc., Computer Geek
> Tel: 408.745.3182 Fax: 408.745.8905
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>
--
Edson Tirelli
JBoss Drools Core Development
JBoss by Red Hat @ www.jboss.com
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