Drools Memory Challenges

[Raja Mahendrakar]

Hello Drools Team,

We are currently using Drools in our application, and we are observing very high memory usage during rule execution.

To troubleshoot this issue, we tried multiple Drools execution approaches and configurations.


To optimize execution, we tried using a precompiled Drools KJAR approach. The rules are built and packaged as a KJAR, and at runtime we load the
KJAR using KieContainer instead of compiling the rules for every execution.
However, even after using the precompiled KJAR and stateless session approach, memory usage is still very high during Drools execution.


We also tried the equivalent programmatic Drools configurations:

KieBaseConfiguration kieBaseConf = kieServices.newKieBaseConfiguration();

Sequential mode:
kieBaseConf.setOption(SequentialOption.YES);

Parallel evaluation:
kieBaseConf.setOption(ParallelExecutionOption.PARALLEL_EVALUATION);

Fully parallel execution:
kieBaseConf.setOption(ParallelExecutionOption.FULLY_PARALLEL);


Stateless session :
 StatelessKieSession statelessSession = kieContainer.newStatelessKieSession();

Pooled session :
 KieServices ks = KieServices.Factory.get();
 KieContainer container = ks.newKieContainer(kieModule.getReleaseId());

 KieSessionsPool pool = container.newKieSessionsPool(poolSize);

Precompiled KIE base / KIE container approach:
 KieContainer kieContainer = kieServices.newKieContainer(releaseId);
 KieBase kieBase = kieContainer.getKieBase();


However, even after trying sequential, stateless, precompiled, parallel, fully parallel, and pooled configurations, the memory consumption remains
high and is affecting our application performance.

Could you please help us understand the possible reasons for this high memory usage and suggest the best Drools configuration or optimization
 approach for our use case?


We would appreciate guidance on the following:

* Which Drools configuration is recommended for lower memory
* we have ariund 5000 rules in our drl file and taking around 150MB of memory

Drools Version: 9.44.0.Final

Thank you for your support.

[Alex Porcelli]

Please upgrade to recent version of drools release: 10.2.0

9.44 is way old and not maintained anymore. Once you do it, please report back.

-

Alex

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[Raja Mahendrakar]

Hi Alex/ Team,

Thank you for your reply, we have upgraded the drools version to 10.2.0 and still see the memory usage is high.

Could you please let us know what else can be done to reduce to memory usage.

[Abhijit Humbe]

Which drools version you were using earlier ? And how much memory was consumed for 5000 rules ? I think for 5000 rules 150mb heap usage is fine. 

 

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[Raja Mahendrakar]

We were using drools version "9.44.0.Final".
we have multiple such files with over 5k rules and if it takes over 150MBand load simultaneously, memory will spike and get OutOfMemory issues. 

Please suggest on how we can reduce the heap memory.