[rules-users] Needs advice to help Drools on a big problem (and avoid GC overhead)

[Mark Proctor]

Did you try using the engine in equality mode? It will only ever allow one “equal” object to be inserted, others are just ignored.

Mark
On 20 Mar 2014, at 18:54, Raphael <raphael.jolivet at gmail.com> wrote:

> Hi,
> 
> In our project, we use Drools to compute forbidden allocations as input for
> an allocation problem  (for which we do not use Drools BTW).
> 
> The constraint of the problem (forbidden operation for given resources) are
> expressed as drools rules.
> 
> We have about
> -200 resources
> -700 operations
> 
> Those are the Drools facts.
> We have about 200 Drools rules describing the forbidden allocations
> 
> The problem here is that many rules produce duplicates forbids.
> For instance :
> Rule 1 may forbid Op1 on Res1 & Res3
> Rule 2 may forbid Op1 on Res2 & res3
> 
> Currently the RHS of rules just insert forbids into a pure Java Set (no fact
> insertion).
> The Set takes care of avoiding duplicates, but still, we feel we could help
> Drools by giving him a hint that
> all rules are actually producing pairs of <Resource, Allocation> and that he
> should not try to produce them more than once.
> 
> Currently the structure of each rule looks like that :
> 
> when
> $resource : Resource(<someconditions>)
> $operation : Operation(<someconditions>)
> then
>  globalSet.add(Pair<resrouce, operation>) 
> end
> 
> With the size of the problem, we often end up with outOfMem/ GC limit.
> When analyzing memory dump, we see about 
> 300.000 drools left tuple object.
> 
> I am not sure if we could help drools to reduce the Rete tree here.
> I mean, the allocation matrix is already : 200*700 = 140.000 cells.
> Drools only uses 2 nodes for each possible forbids, which seems already well
> optimized.
> 
> We had several idea to improve that though, but we are not enough expert in
> the internal of the RETE algorithm to decide if that's a good way to go :
> 
> 1) Insert forbids as facts in the RHS and check they are not already there
> in the LHS :
> when
> $resource : Resource(<someconditions>)
> $operation : Operation(<someconditions>)
> not Forbid(res=$resource, op=$operation)
> then
>  insert(Forbid($resource, $operation))
> end
> 
> 2) Merge all rules in one big rule with a single RHS
> Is it possible to have something like :
> when
> // Rule 1 
> ($resource : Resource(<someconditions>)
> $operation : Operation(<someconditions>))
>  or
> // Rule 2 
> ($resource : Resource(<someconditions>)
> $operation : Operation(<someconditions>))
> // Etc ...
> then
>  globalSet.add(Pair<resrouce, operation>) 
> end
> 
> 3) Define a common RHS somewhere and tell Drools all rules use this one.
> Is there a possibility in Drools to define reusable RHS ? Would it help ?
> 
> 4) Any other idea ?
> 
> 
> Thanks in advance for your help.
> Brgds,
> 
> Raphael Jolivet
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --
> View this message in context: http://drools.46999.n3.nabble.com/Needs-advice-to-help-Drools-on-a-big-problem-and-avoid-GC-overhead-tp4028838.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users