Miguel,

    First we need to understand where is this memory spent. Drools externalizes the actual rule compilation to a java compiler (JDT or Janino) and I would not be surprised if compiling 2100 rules would consume more than 300Mb **during compilation**. I don't think that after compiling, the application will continue to use that amount of memory just because of rules, although if you have many facts being inserted into your session, it obviously will drive consumption up.

    So, some questions:

1. Do you use one KnowledgeBuilder to compile all your rule files or do you use one KnowledgeBuilder per file?

2. How much memory is your application using during this step, where you add resources to your knowledgeBuilder(s)?

3. After compiling your knowledge packages, did you tried to force a GC to check how much memory it continues to use?

4. Are you adding all rules to the same KnowledgeBase or using one kbase per set of rules? How much memory are you consuming in this step?

5. Did you tried compiling it once, generating the kbase and serializing it to a file, and then, instead of recompiling everything, just deserialize the file into memory and using it? How much memory it consumes when you deserialize from a file?

   Knowing the answer to the above questions will help to determine if you have a problem and how to work around it or fix it.

Hi Miguel,

I assume that you've used a memory analyzer to find out conclusively that the memory usage is by Drools, and not a memory leak?

One way to do this is to limit the virtual memory to a small amount, add -XX:+HeapDumpOnOutOfMemoryError to your environment, and then using Memory Analyzer to analyse the dump.

Cheers
Jevon

On Wed, Mar 31, 2010 at 2:44 AM, Miguel Machado <mls.machado <at> gmail.com> wrote:

hi all,

I'm quite new to the drools rule engine and i've been using it for a project where i need to filter events and execute actions accordingly.

I'm currently running a DRL file and creating a stateful session from it, and then running 2/3 facts every time. Every X seconds I collect the available facts and call fireAllRules() + dispose(), always within the same session. The DRL file has circa 2160 rules declared (an external program is producing them), and i'm using the "no-loop", "lock-on-active", "activation-group" and "agenda-group" options on almost every one.

My main problem is that the software is consuming too much memory when it loads the rules to the knowledge base variable, it reaches +300Mb which is just not affordable in this project. Is there any way i can work around this? I've tried setting some configuration properties but to no avail. What techniques may i try in order to reduce memory load on drools startup? What would be the best approach for dealing with so many rules?

Anything would help, thanks in advance,

_ miguel

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I have a ruleflow that handles exceptions when they are raised by a "Fault"
node but I am not being able to accomplish the same if an exception is
thrown by a workItem or an action node instead.

I have a workItem node with a work item handler that throws a
RuntimeException. My exception handler in the composite node is not catching
this exception.

So, question
1) how can I handle runtime exceptions thrown by my workItemHandlers?
2) how can I get a hold of the exception to log the stack trace?

Any ideas or tips are very appreciated.

Nick.
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