[rules-users] Problems Extending the Golfer example - Cartesian joins ??

[Mark Proctor]

I must admit I didn't check against this example. But we did find a 
memory leak. Each activation remembers its parent activation, this chain 
was never getting nulled, which meant for recursive algorithms it went 
out of memory very quickly - this is now fixed. Maybe you can check 
trunk and make sure that fixes our problem? Trunk is broken at the 
moment, while we do MVEL updates, but should be fixed in a few hours. 
I'll message the list when it is - you won't need to build anything 
yourself as you will then be able to get the latest snapshot to try from 
here http://cruisecontrol.jboss.com/cc/artifacts/jboss-rules.

Mark
Simon French wrote:
> Hi Mark,
> After all the hard work you guys have put into drools recently I hope 
> you had a good holiday.
> Has anybody had a chance to look at this?
>
> Simon
>
> On 20/07/07, * Mark Proctor* <mproctor at codehaus.org 
> <mailto:mproctor at codehaus.org>> wrote:
>
>     we'll look into this to see where the memory is going. but won't
>     be for another week or so - I'm currently on holiday.
>
>     Mark
>     Simon French wrote:
>>     Hi,
>>     After attending a session with Mark Proctor in London I was
>>     inspired to play around with Drools in a slightly different way
>>     than we use it for in the workplace, and try and solve a puzzle.
>>     Unfortunately I couldn't get Drools to solve it as I kept getting
>>     memory problems (I believe are cartesian joins being the problem),
>>     so I decided to extend the golfer example to see if I got the
>>     same problem
>>     I added two new names and a new integer property, club
>>
>>             // create all possible Golfer objects
>>                     String[] names = new String[] { "Fred", "Joe",
>>     "Bob", "Tom", "Des", "Terry" };
>>                     String[] colors = new String[] { "red", "blue",
>>     "plaid", "orange","black", "white" };
>>                     int[] positions = new int[] { 1, 2, 3, 4, 5, 6 };
>>                     int[] clubs = new int[] {9,8,7,4,5,5};
>>                    
>>                     for ( int n = 0; n < names.length; n++ ) {
>>                        for ( int c = 0; c < colors.length; c++ ) {
>>                               for ( int p = 0; p < positions.length;
>>     p++ ) {
>>                                   for ( int q = 0; q < clubs.length;
>>     q++ ) {
>>                                       session.insert(new Golfer(
>>     names[n], colors[c], positions[p], clubs[q]) );
>>
>>     ....
>>
>>
>>     Then changed the golder.drl to:
>>
>>     package com.sample
>>
>>     import com.sample.Golfer;
>>
>>
>>     rule "Golfer Riddle"
>>         when
>>             // A golfer named Fred,
>>            
>>             Golfer( name == "Fred",
>>                     $fredsPosition : position, $fredsColor : color,
>>     $fredsClub : club   )
>>
>>             // Der Golfer hinter Fred trägt blau
>>             Golfer( $unknownsName : name != "Fred",
>>                     $unknownsPosition :  position == ( $fredsPosition
>>     + 1 ),
>>                     $unknownsColor : color == "blue", color !=
>>     $fredsColor,
>>                     $unknownsClub : club == 5 )
>>
>>             // Joe steht an zweiter Stelle               
>>             Golfer( name == "Joe", $joesPosition : position == 2,
>>                     position != $fredsPosition,
>>                     $joesColor : color != $fredsColor,
>>                     $joesClub : club == 5 )
>>
>>             // Bob traegt Karo       
>>             Golfer( name == "Bob",
>>                     name != $unknownsName,
>>                     $bobsPosition : position != $fredsPosition,
>>                     position != $unknownsPosition, position !=
>>     $joesPosition,                                                 
>>                     $bobsColor : color == "plaid",
>>                     color != $fredsColor, color != $joesColor,
>>                     color != $unknownsColor,
>>                     $bobsClub : club < $joesClub )
>>
>>             // Tom ist nicht 1. oder 4., traegt kein Orange
>>             Golfer( $tomsName : name == "Tom",
>>                     $tomsPosition : position != 1, position != 4,
>>                     position != $fredsPosition, position !=
>>     $joesPosition,
>>                     position !=
>>     $bobsPosition,                               
>>                     $tomsColor : color != "orange", color != "blue",
>>                     color != $fredsColor, color != $joesColor,
>>                     color != $bobsColor ) 
>>
>>             Golfer ( $des : name == "Des", $desPosition : position <
>>     $fredsPosition, $desColor : color != "blue",
>>                     color != $fredsColor, color != $joesColor,
>>                     color != $bobsColor )
>>             Golfer ( $terry : name == "Terry", $terryPosition :
>>     position < $desPosition, $terryColor : color != "blue",
>>                     color != $fredsColor, color != $joesColor,
>>                     color != $bobsColor )
>>         then
>>             System.out.println( "Fred " + $fredsPosition + " " +
>>     $fredsColor );
>>             System.out.println( "Joe " + $joesPosition + " " +
>>     $joesColor );
>>             System.out.println( "Bob " + $bobsPosition + " " +
>>     $bobsColor );
>>             System.out.println( "Tom " + $tomsPosition + " " +
>>     $tomsColor );  
>>             System.out.println ( "Des " + $desPosition + " " +
>>     $desColor );  
>>             System.out.println( "terry " + $terryPosition + " " +
>>     $terryColor );  
>>     end
>>
>>
>>     After a couple of minutes of processing I got:-
>>
>>     Exception in thread "main" java.lang.OutOfMemoryError: Java heap
>>     space
>>
>>     I also changed java memory allocation with -Xms1640M -Xmx1640M
>>     (The most I can allocate on my PC), and tried running it as a
>>     stateless  session too.
>>
>>     Is there anything else I can do, or is this simply pushing drools
>>     too far (surely not!!) ?
>>
>>     I'm very keen on pushing this technology as much as possible in
>>     our workplace and I'd really appreciate any help.
>>
>>     Thanks in advance
>>
>>     Simon
>>
>>     ------------------------------------------------------------------------
>>
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>>       
>
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