[jboss-jira] [JBoss JIRA] Commented: (JBRULES-1572) sometimes getting ClassFieldExtractor error

[Ming Fang (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBRULES-1572?page=comments#action_12410809 ] 
            
Ming Fang commented on JBRULES-1572:
------------------------------------

I think the problem is due to a race condition in BinaryHeapQueue, the activation is being fired twice.
The second time around the fact has already been retracted causing the exception.

Note this not example the same error as this issue says but it is the same cause.

> sometimes getting ClassFieldExtractor error
> -------------------------------------------
>
>                 Key: JBRULES-1572
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-1572
>             Project: JBoss Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>    Affects Versions: 5.0.0-M1, 4.0.4, 4.0.7
>            Reporter: Ming Fang
>         Assigned To: Mark Proctor
>         Attachments: Foo.java, rule.drl, Test.java
>
>
> Caused by: java.lang.NullPointerException
> 	at org.drools.base.com.ml.ax.ModelValue10285014$getModelValue.getDoubleValue(Unknown Source)
> 	at org.drools.base.ClassFieldExtractor.getDoubleValue(ClassFieldExtractor.java:191)
> 	at org.drools.rule.Declaration.getDoubleValue(Declaration.java:281)
> 	at com.ml.ax.drools.Rule_Quote_0ConsequenceInvoker.evaluate(Rule_Quote_0ConsequenceInvoker.java:17)
> 	at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:586)
> This only happens sometimes but it completely breaks my program.

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