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.