[rules-users] How to make this rule more memory efficient?

Tue May 4 11:55:14 EDT 2010

Hi Thomas,

You are correct in your interpretation of what I want to do.

I did consider adding the mappings as their own facts but I was concerned that the sheer number of them would overload drools. For each Cell instance, it can refer to up to 60 ProxyCell instances. With 20,000 Cell instances (in my proto-type), that means 1.2 million mappings.

Can drools handle these kinds of numbers of facts?

Thanks,
Ryan. 

-----Original Message-----
From: rules-users-bounces at lists.jboss.org [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Swindells, Thomas
Sent: 28 April 2010 10:17
To: Rules Users List
Subject: Re: [rules-users] How to make this rule more memory efficient?

If I understand the following
> What I want to do is find out where I have a reference from any 
> instance of Cell - cell1 - to any instance of ProxyCell - proxycell2 - 
> but am missing a reference from cell2 to proxycell1 where proxycell2 
> is a representation of
> cell2 and proxycell1 is a representation of cell1.

What I think you saying is that if
C1 -> P2 then there must be a C2 -> P1
Where C2 == P2.cellId and P1 == C1.cellId.

I've not worked this through properly (It's still too early in the working day) but do you may make a win by inserting the mappings into working memory as their own facts (and so trading memory for processing time).  You can then reason over these relationships which should reduce the number of combinations that are made.
So have a rules like the following:

Rule "createRelationship" salience [high]
$cell1 : Cell()
$proxy2 : Proxy($cell1.relationships contains this.name) then insert new Relationship($cell1.id, $proxy2.id); end

Rule "check inverse" salience [low]
$relationship : Relationship()
$cell1 : Cell(id == $relationship.cellId)
$proxy2 : Proxy(id == $relationship.proxyId) not exist Relationship(cellId == $relationship.proxyId, proxyId == relationship.cellId) then //raise warning or whatever end

Hopefully this does what you wants and should be more efficient processing wise and activation count wise.
Thomas

> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org [mailto:rules-users- 
> bounces at lists.jboss.org] On Behalf Of Ryan Fitzgerald
> Sent: 28 April 2010 09:46
> To: Rules Users List
> Subject: Re: [rules-users] How to make this rule more memory efficient?
>
> Thanks Wolfgang.
>
> Should I conclude therefore that high memory usage is unavoidable due 
> to the number of facts that must be processed? I was hoping that there 
> might be a clever way of writing the rules so that the rules engine 
> can minimise the network it generates - even if it takes a little longer to execute.
>
> All of the facts are read from a database and thus loaded into working memory.
> My fallback position is to not load all these objects into working 
> memory but instead embed into a rule, a service call that queries the 
> db for all inconsistencies (effectively using SQL instead of a drools 
> rule). However, since I will have other rules that operate on these 
> objects in working memory, I was hoping to use these facts for all rules.
>
> /Ryan.
>
> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org [mailto:rules-users- 
> bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
> Sent: 27 April 2010 14:59
> To: Rules Users List
> Subject: Re: [rules-users] How to make this rule more memory efficient?
>
> If there are n Cell facts,
>  $cell1 : Cell()
>  $cell2 : Cell()
> needs to create n*n pairs in the network before any reduction may set in.
> Using
>   $cell2 : Cell(this != $cell1)
> reduces this by n, so we're still quadratic. Something like
>  $cell1 : Cell( $id1 : id )
>  $cell2 : Cell( id > $id1 )
> reduces it to n*(n-1)/2 which is less than 50% of the original, but 
> still quadratic.
>
> -W
>
> 2010/4/26 Swindells, Thomas <TSwindells at nds.com>:
> > You should probably restrict it so that
> >
> > $cell2 : Cell(this != $cell1)
> >
> >
> >
> > Thomas
> >
> >
> >
> > From: rules-users-bounces at lists.jboss.org
> > [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Ryan 
> > Fitzgerald
> > Sent: 26 April 2010 15:34
> > To: rules-users at lists.jboss.org
> > Subject: [rules-users] How to make this rule more memory efficient?
> >
> >
> >
> > Hi,
> >
> >
> >
> > Can anyone advise me on how to make a drools rule more memory efficient?
> > Here is the problem:
> >
> >
> >
> > I have a Cell and a ProxyCell object classes.
> >
> >
> >
> > The ProxyCell represents the Cell when their internal ID's match.
> >
> >
> >
> > Each Cell and ProxyCell however has a unique name (not same as ID).
> >
> >
> >
> > A Cell can reference (by name) a ProxyCell (as long as the ProxyCell 
> > does not represent that actual Cell - which would effectively be a 
> > self-reference and is not allowed).
> >
> >
> >
> > What I want to do is find out where I have a reference from any 
> > instance of Cell - cell1 - to any instance of ProxyCell - proxycell2 
> > - but am missing a reference from cell2 to proxycell1 where 
> > proxycell2 is a representation of
> > cell2 and proxycell1 is a representation of cell1.
> >
> >
> >
> > Here is the rule I have written for it:
> >
> >
> >
> > rule "Check consistent references"
> >
> > when
> >
> >         $cell1 : Cell()
> >
> >         $cell2 : Cell()
> >
> >         $proxycell1 : ProxyCell ( id = $cell1.id, $cell2.references 
> > contains this.name )
> >
> >         $proxycell2 : ProxyCell ( id = $cell2.id, $cell1.references 
> > not contains this.name )
> >
> > then
> >
> >         //report an error.....
> >
> > end
> >
> >
> >
> >
> >
> > I have 10,000 instances of Cell and 10,000 instances of ProxyCell in 
> > working memory. For each instance of Cell, it can have references to 
> > 60 different ProxyCell instances. Loading the Cell and ProxyCell 
> > instances into working memory is not a problem. However, when I try 
> > to run this rule above, the memory quickly goes above 1GB and I 
> > eventually get
> an out of memory error.
> >
> >
> >
> > I was wondering if there is a better way to structure or write this 
> > rule so that it doesn't use so much memory.
> >
> >
> >
> > Thanks,
> >
> > Ryan.
> >
> >
> >
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This message is confidential and intended only for the addressee. If you have received this message in error, please immediately notify the postmaster at nds.com and delete it from your system as well as any copies. The content of e-mails as well as traffic data may be monitored by NDS for employment and security purposes.
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