[rules-users] How can I know, how many facts are processed by stateFulSession?

Hello, I have a class and rule: class CTestObj { private double value; void setValue(double v) { this.value = v; } double getValue() { return this.value; } } rule "r1" when p : CTestObj then p.setValue( 1 / p.getValue() ); end As you can see, in this rule, there is risk, to put into stateFulSession object with value set 0. I can't validate this, because, this problem has a variation where I put into stateFulSession object with set no 0, but the rule will modify it... So - I can't validate this = fact with value 0 is correct. But I process with stateFulSession many, many facts... For example 1000. And, after 900 facts it occurs, that fact number 901 has value set on 0. In effect I get an exception: org.drools.runtime.rule.ConsequenceException: java.lang.ArithmeticException: / by zero. And ksession stops processing facts. But, 900 facts are processed! I don't want to process them second time. And this is my question: How can I know, which fact is first no-processed fact? Which one stoped fireAllRules method? Beacuse I don't want to process them another time. Greetings :) tom.