Re: [rules-dev] Why is this DRL twice as slow?
But even if it get re-evaluated twice, it cannot explain a performance
loss of more then 5%, let alone a a performance loss of 150%?
If you take a look at the accumulate sum function implementation, you
'll see that the total gets cached.
That's also why an accumulate has "action code" and "reverse
code".
So since that sum total gets cached, I see no reason why this line:
$hardTotal : Number() from accumulate ...
would take any noticeable time?
I have a very strong feeling for a long time that accumulate functions
are poison for drools-solver. Yet I see no way to workaround them.
Maybe we need some sort of "forward chaining accumulate" implementation?
With kind regards,
Geoffrey De Smet
Greg Barton schreef:
As I understand it, the from keyword is not optimized in the way that
it's output is not indexed. Therefore if the set of objects matched changes it must
rerun. So when you have the two rules, "hardConstraintsBroken" is reevaluated
when you change the hard constraints, and "softConstraintsBroken" is reevaluated
when you change the soft constraints. When there's just the one rule, it's
reevaluated when either the hard or soft constraints changed, but BOTH accumulate
expressions are evaluated every time. Thus, 2x the evaluation time.
--- On Sat, 8/8/09, Geoffrey De Smet <ge0ffrey.spam(a)gmail.com> wrote:
> From: Geoffrey De Smet <ge0ffrey.spam(a)gmail.com>
> Subject: [rules-dev] Why is this DRL twice as slow?
> To: rules-dev(a)lists.jboss.org
> Date: Saturday, August 8, 2009, 5:46 AM
> Hi guys,
>
> I've run some experiments on the DRL's used in the drools
> solver
> examination example to see how the DRL affects
> performance.
>
> In one experiment, I merged 2 rules into 1 rule:
>
> I changed this DRL part of examinationScoreRules.drl:
>
> rule "hardConstraintsBroken"
> salience -1
> when
> $hardTotal :
> Number() from accumulate(
>
> IntConstraintOccurrence(constraintType ==
>
> ConstraintType.NEGATIVE_HARD, $weight : weight),
>
> sum($weight)
> );
> then
>
> scoreCalculator.setHardConstraintsBroken($hardTotal.intValue());
> end
>
> rule "softConstraintsBroken"
> salience -1
> when
> $softTotal :
> Number() from accumulate(
>
> IntConstraintOccurrence(constraintType ==
>
> ConstraintType.NEGATIVE_SOFT, $weight : weight),
>
> sum($weight)
> );
> then
>
> scoreCalculator.setSoftConstraintsBroken($softTotal.intValue());
> end
>
>
>
> into this DRL part:
>
> rule "constraintsBroken"
> salience -1
> when
> $hardTotal :
> Number() from accumulate(
>
> IntConstraintOccurrence(constraintType ==
>
> ConstraintType.NEGATIVE_HARD, $weight : weight),
>
> sum($weight)
> );
> $softTotal :
> Number() from accumulate(
>
> IntConstraintOccurrence(constraintType ==
>
> ConstraintType.NEGATIVE_SOFT, $weight : weight),
>
> sum($weight)
> );
> then
>
> scoreCalculator.setHardConstraintsBroken($hardTotal.intValue());
>
> scoreCalculator.setSoftConstraintsBroken($softTotal.intValue());
> end
>
>
> Now the performance for a 100 steps when from 71s to 172s,
> so it more
> then doubled.
> All other code stayed the same and the output (except for
> the times) is
> exactly the same.
> What can explain this loss in performance?
>
> --
> With kind regards,
> Geoffrey De Smet
>
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