[jboss-jira] [JBoss JIRA] (DROOLS-4645) High memory consumption with JIT

[Radovan Synek (Jira)]

Radovan Synek created DROOLS-4645:
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             Summary: High memory consumption with JIT
                 Key: DROOLS-4645
                 URL: https://issues.jboss.org/browse/DROOLS-4645
             Project: Drools
          Issue Type: Bug
          Components: executable model
    Affects Versions: 7.29.0.Final
            Reporter: Radovan Synek
            Assignee: Luca Molteni


Employee Rostering example for OptaPlanner shows excessive memory consumption, which is connected with Drools score calculation.

Please see the reproducer - running it without drools JIT finishes on time with 3GB of memory while with drools JIT being active it fails due to "GC overhead limit exceeded" despite the fact it god twice as much memory.

Logging (add -Dlogback.level.org.optaplanner=trace to the execute_jit.sh script) showed there is a huge pillar move changing ~hundreds of entities which takes seconds to calculate score. During this move's evaluation, the memory consumption increases to a point when GC takes over and later fails. 

Memory sampling and heap dump investigation showed there are ~10^7 objects of org.drools.core.reteoo.FromNodeLeftTuple class, taking more memory than any other data type in the VM.

See the attached screenshots.





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