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

[Artur Kronenberg (JIRA)]

Artur Kronenberg created DROOLS-1030:
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             Summary: Nullpointer in JpaTimerJobInstance.call on startup 
                 Key: DROOLS-1030
                 URL: https://issues.jboss.org/browse/DROOLS-1030
             Project: Drools
          Issue Type: Feature Request
          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


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! 



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