[jboss-jira] [JBoss JIRA] (DROOLS-1030) Nullpointer in JpaTimerJobInstance.call on startup

[Artur Kronenberg (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-1030?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13153927#comment-13153927 ] 

Artur Kronenberg edited comment on DROOLS-1030 at 2/5/16 12:51 PM:
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For the people coming here with the same issue, this is the workaround I implemented:

1. Add a new Interface with say one method isExpired(). This method determines whether or not the fact can go. 
2. Add a rule to match that interface. For me the Interface is called Expirable. This is my rule:

rule "fact_expiry_automation"
    when
        $e : Expirable( expired == true );
    then
        retract($e);
end

3. Have all your facts implement that interface.
4. Add a timer task manually that calls fireAllRules. Use an AgendaFilter in case you want to only match this rule exactly.
5. Run the task as often as you wish. 

You will also have to remove the expires annotation on the original facts to stop drools from also trying to expire facts. 

This solution has an issue where the expiry for the facts only work if the facts are inserted on session level. For example, I had to restructure my rules to not use entrypoints so that these facts could also expire programatically. 

Hope that helps 

UPDATE: not actually working because a fact is not reevaluated. My new workaround: 

The timer task inserts a new ExpiryFact each time it runs. That way there's a new fact that must be evaluated. The fact caries an expiryTimestamp that i can then compare with the expiry field on my other facts. 


was (Author: pandaadb):
For the people coming here with the same issue, this is the workaround I implemented:

1. Add a new Interface with say one method isExpired(). This method determines whether or not the fact can go. 
2. Add a rule to match that interface. For me the Interface is called Expirable. This is my rule:

rule "fact_expiry_automation"
    when
        $e : Expirable( expired == true );
    then
        retract($e);
end

3. Have all your facts implement that interface.
4. Add a timer task manually that calls fireAllRules. Use an AgendaFilter in case you want to only match this rule exactly.
5. Run the task as often as you wish. 

You will also have to remove the expires annotation on the original facts to stop drools from also trying to expire facts. 

This solution has an issue where the expiry for the facts only work if the facts are inserted on session level. For example, I had to restructure my rules to not use entrypoints so that these facts could also expire programatically. 

Hope that helps 

> Nullpointer in JpaTimerJobInstance.call on startup 
> ---------------------------------------------------
>
>                 Key: DROOLS-1030
>                 URL: https://issues.jboss.org/browse/DROOLS-1030
>             Project: Drools
>          Issue Type: Bug
>          Components: core engine
>         Environment: Mac OS 10.10.5, Eclipse Mars Release, Java 1.8, Drools 6.3.0.Final
>            Reporter: Artur Kronenberg
>            Assignee: Mario Fusco
>             Fix For: 6.4.0.CR1
>
>         Attachments: test-standalone.zip
>
>
> Hi,
> I have noticed Nullpointer exceptions when I try and reload a persisted session on startup. It is a bit hard to recreate (I am actually not managing it now since I deleted all old sessions to attempt recreation) but I figured maybe someone has an idea. Essentially I am getting this NPE twice:
> java.lang.NullPointerException: null
>         at org.drools.persistence.jpa.JpaTimerJobInstance.call(JpaTimerJobInstance.java:50) [drools-persistence-jpa-6.3.0.Final.jar:6.3.0.Final]
>         at org.drools.persistence.jpa.JpaTimerJobInstance.call(JpaTimerJobInstance.java:30) [drools-persistence-jpa-6.3.0.Final.jar:6.3.0.Final]
>         at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_51]
>         at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_51]
>         at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_51]
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_51]
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_51]
>         at java.lang.Thread.run(Thread.java:745) [na:1.8.0_51]
> When debugging I noticed the following behaviour which points to a race condition: 
> If I start my server and try to recreate the session, those NPEs happen 2x.
> If I start my server and put a breakpoint BEFORE creating the CommandService for execution, I can wait for a few seconds and the service can be found.
> It appears that the scheduler's timerJobFactoryManager is not fully there at the time the sessions is being loaded? Or something else is racing with the service creation. 
> Is there a way for me to make sure everything is fully instantiated before I use drools? Does a workaround exist? Is this even a bug? 
> Thanks and let me know your thoughts. If I run into this again I will attempt to try and reproduce it. Let me know if more info is needed!
> UPDATE:
> I noticed that the reason I can't reproduce it at the moment is that the JpaTimerJobInstance is never called with the newly persisted session. It appears that that timer job depends on something else to happen so that it thinks it needs to start the timerJob 



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