Corrupted KieBase object? - drools

Question

Due to performance consideration, we try to re-use the same KieBase object to spawn new KieSession to for each rule invocation against the same ruleset. Everthingyth works well until after a period of time when all of a sudden, the newly created kieSession from the cached kieBase stops firing the rules that it was supposed to.
But as soon as we get rid of the cached kieBase and re-create a new kieBase and new a kieSession with it, it starts working again.
Our understanding is that kieBase object does not hold session-specific data. But the behavior seems to indicate that the cached kieBase is subject to being tampered over time.
The version we are using is 6.3.0.Final.
Any hints on this would be highly appreciated.

Answer 1

I had this issue, too. After creating 20 sessions in rapid succession, the 21st session would throw a ClassCastException on a cast to BigDecimal in this rule even though runs on the previous 20 sessions did not:
rule IsMaterialChange_TotalMonthlyIncomeAmountUpdate when
Data("TOT_MO_INCM_AMT-ORIGINAL_VALUE"; $originalTotalMonthlyIncomeAmount : value)
Data("TOTALMONTHLYINCOMEAMOUNT"; (BigDecimal) value != (BigDecimal) $originalTotalMonthlyIncomeAmount)
then
insert(new IsMaterialChange("TotalMonthlyIncomeAmountUpdate", true));
end
After digging around for a bit, I found this answer that pointed to the JIT compiler as the cause. It has a default threshold of 20 which lined up exactly with my issue. For some reason the JIT compiler has problems casting this value.
I disabled the JIT compiler like this:
KieContainer kieContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId());
KieBaseConfiguration kieBaseConfiguration = kieServices.newKieBaseConfiguration();
// Disable JIT Compiler to prevent ClassCastException BigDecimal
kieBaseConfiguration.setOption(ConstraintJittingThresholdOption.get(-1));
KieBase kieBase = kieContainer.newKieBase(loaderKey, kieBaseConfiguration);