[rules-users] Drools compiler memory & stateless sessions?

Wed Nov 26 14:35:46 EST 2008

Amit Mhatre wrote:
> hi, I was facing similar issues some time back, though I was using a 
> ruleflow and had >20000 fact objects evaluated daily. The problem I 
> was facing was that the running time would get significantly slower 
> day by day. The solution that fixed it was to use a statefulSession 
> and call dispose() on the session once it is done. This made a 
> single-run slower than before, but atleast fixed the problem of 
> exponentially increasing the run-time after several days.
This sounds like a bug. Stateless session should definitely not get 
repeatedly slower - as it's really just conenience wrapper around a 
stateful session.
>
> This might not necessarily be the ideal solution, so before you move 
> to a StatefulSession and call session.dispose() after processing, you 
> might want to try to increase the memory for the jvm, if is lower than 
> the size of your facts, this might fix it.
Maybe someone can review the stateless session code and try and find 
where the memory leak is coming from?
>
> It'd be useful to know if somebody has a better solution to Kris's 
> problem.
>
> Thanks,
> - am
>
>
> On Wed, Nov 26, 2008 at 9:35 AM, Kris Nuttycombe 
> <kris.nuttycombe at gmail.com <mailto:kris.nuttycombe at gmail.com>> wrote:
>
>     Hi, all,
>
>     I'm encountering significant problems with running out of memory
>     when executing a small ruleset (only 16 rules, < 100 facts). I've
>     run jmap on the process (which has previously spawned multiple
>     stateless sessions in parallel) and it looks like Drools, and
>     specifically the Eclipse jdt compiler, is seriously eating up
>     memory. The code calling the is fairly simple; one of the initial
>     facts is an accumulator that I refer to later:
>
>             StatelessSession session = ruleBase.newStatelessSession();
>             session.execute(initialFact, accumulator);
>
>             accumulator.doSomething();
>
>     where ruleBase is a shared instance, and initialFact is a base
>     fact that is expanded during rules processing. Is there something
>     I should be doing to dispose the session after use to release the
>     objects created by the drools compiler after use? I'm using a
>     shared RuleBase, and I'm wondering whether it is somehow keeping
>     references around. Are these sorts of object counts to be expected?
>
>     Thanks,
>
>     Kris
>
>
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>
> -- 
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> -- Kurt Cobain
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