[rules-users] Consequence Exception with too many events

[Jason Barto]

Wolfgang,
thank you for your prompt reply.  After further work with my code I think
the culprit may have either been the setting of the event expiration time
to 1s OR that I was using session.update to insert a new counter object;
but maybe not.  I cleaned up my code in order to send it out.  In doing so
I also downloaded the official Drools 5.5 distribution (in the previous
example I was using the libraries packaged with BRMS).  Between the code
cleanup and the use of the official distro I'm no longer experiencing a
Consequence Exception.

That being said I am still experiencing a NPE when a high iteration count.
If you take a look at Drools5FusionEval.java, around line 51 you'll see a
variable 'eventLimit'.  If set to 500000 it seems to pretty reliably kick
out the following NPE:

Exception in thread "Thread-1" java.lang.NullPointerException
    at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1319)
    at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1221)
    at
org.drools.common.DefaultAgenda.fireUntilHalt(DefaultAgenda.java:1434)
    at
org.drools.common.AbstractWorkingMemory.fireUntilHalt(AbstractWorkingMemory.java:755)
    at
org.drools.common.AbstractWorkingMemory.fireUntilHalt(AbstractWorkingMemory.java:731)
    at
org.drools.impl.StatefulKnowledgeSessionImpl.fireUntilHalt(StatefulKnowledgeSessionImpl.java:247)
    at drools5fusioneval.Drools5FusionEval$1.run(Drools5FusionEval.java:47)

As I've said I'm still very new to Drools and trying to understand better
how it does what it does - any information that anyone can provide to help
me understand why the above error is being experienced would be greatly
appreciated.

Source code and rules are attached.

Sincerely,
Jason


On Sat, May 4, 2013 at 7:58 AM, Wolfgang Laun <wolfgang.laun at gmail.com>wrote:

> Works for me (5.5.0, 5.4.0) - at least based on the code you've posted
> which (apart from the omitted getters and setters) isn't the one you've
> been running, and so you may have changed or omitted something
> that's essential.
>
> The full stack dump might shed some more light on this, and the full and
> true code of the rule RHS whre the NPE is caused.
>
> -W
>
> On 04/05/2013, Jason Barto <jason.p.barto at gmail.com> wrote:
> > I am new to Drools (Expert and Fusion) and have been reading through the
> > materials over the last few days.  After going through some of the
> tutorial
> > code I wrote a very quick and dirty to perform a base assessment of the
> > speed of Fusion / Expert.  My code is below.  The strange thing I'm
> > currently receiving is, if I insert 100k events the test completes
> > successfully, if I insert 150k events, I receive a ConsequenceException
> > caused by an NPE.  Being new to Drools I must be doing something wrong,
> can
> > anyone please provide some guidance?
> >
> > (Main function)
> > Counter cc = new Counter ();
> > session.insert (cc);
> > for (int i = 0; i < 150000; i++) {
> >   entryPoint01.insert (new MyEvent ());
> > }
> >
> > (Counter Class)
> > public class Counter {
> >   private long total = 0;
> >   // get / set total
> >   public void addValue (int val) {
> >     total += val;
> >   }
> > }
> >
> > (MyEvent Class)
> > public class MyEvent {
> >   private int value = 1;
> >   // get / set value
> > }
> >
> > (DRL file)
> > declare MyEvent
> >   @role (event)
> >   @expires (1s)
> > end
> >
> > rule "Count the rules"
> > when
> >   $ev : MyEvent () from entry-point entryPoint01
> >   $pc : Counter ()
> > then
> >   $cc.addValue ($ev.getValue ());
> > end
> >
> _______________________________________________
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>
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