On 4 May 2012 19:16, Mike Goldner <mike@thegoldners.com> wrote:
Wolfgang,Unfortunately, it would be very difficult to introduce a procedural/algorithmic "branch" into the program flow.
Would it be possible to mimic a procedural approach within the rule using an accumulate function to extract the desired array element and then process the rest of the rule's login?
Mike Goldnerm: 617.909.3009From: Wolfgang Laun <wolfgang.laun@gmail.com>
Reply-To: Rules Users List <rules-users@lists.jboss.org>
Date: Friday, May 4, 2012 1:05 PM
To: Rules Users List <rules-users@lists.jboss.org>
Subject: Re: [rules-users] Performance issues with a rule that includes LHS functionsLooks like an anti-pattern to me: you can expect O(n^3) effort for inserting Data facts.
This is something where a procedural/algorithmic solution is preferable to a
rule based solution.
-W
On 4 May 2012 18:44, Mike Goldner <mike@thegoldners.com> wrote:I have a rule that is suffering severe performance degradation as I insert
facts into the (stateful) session. In my simplified example, the first
100 fact insertions take less than 10ms per fact. By the 1000th fact,
insertions are taking about 850ms per fact. In production, the impact is
much more severe, reaching 5000ms or more by the 1000th insertion. The
number of facts per execution can vary from a few hundred to a few
thousand.
I've created a simplified example that demonstrates the problem: Imagine
that there is a line plotted through a 3-dimensional plane and it is
necessary to ensure that each plotted coordinate is an equal distance from
the adjacent coordinates. I realize that the math isn't correct, but it
is sufficient for the example.
The constraint (and source of performance degradation) imposed by my data
source is that the plane (X, Y, or Z) is variable and it is defined by an
separate index that serves as a pointer into the coordinate list. If I
remove the function calls, the problem disappears.
Any suggestions on how I could rewrite the rule?
Here is my rule:
package test;
declare Data
plane : int
coordinates : java.util.List
end
rule "Performance degradation with functions."
dialect "mvel"
when
$current : Data( $currentPosition : getPosByAxis(plane, coordinates) )
$before : Data( $beforePosition : getPosByAxis(plane, coordinates) <
$currentPosition)
not Data( getPosByAxis(plane, coordinates) > $beforePosition && <
$currentPosition)
$after : Data($afterPosition : getPosByAxis(plane, coordinates) >
$currentPosition)
not Data(getPosByAxis(plane, coordinates) < $afterPosition && >
$currentPosition)
eval ( ($currentPosition - $beforePosition) == ($afterPosition -
$currentPosition) )
then
System.out.println("Rule RHS fired.");
end
function Double getPosByAxis(int plane, java.util.List coordinates) {
return (Double) coordinates.get(plane);
}
Thanks,
Mike Goldner
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