[rules-users] Does JIT give me a hard time?

[wasperen]

Hi,

I have been using Drools for some years now and really happy with it!

But I am struggling now with the 5.4 version. It seems that the JIT compiler
does not like me. For example, I have a rule that says:

rule "activate operations, for operator"
	when
		$worker : VCMShiftWorker( selectQuery == "operatorSelect" )
		$ea : ExecutableAction(
			action.subject.parentActionable != null,
			$worker.isUnderManagement( action.subject.parentActionable )
		)
		not RelevantExecutableAction(
			$worker;
			executableAction != $ea,
			executableAction.priority > $ea.priority ||
			(executableAction.priority == $ea.priority && executableAction.workTime >
$ea.workTime) ||
			(executableAction.priority == $ea.priority && executableAction.workTime
== $workTime && $critical && ! executableAction.critical)
		)		
	then
		System.out.println($worker+" makes relevant :"+$ea);
		insert( new RelevantExecutableAction( $worker, $ea ) );
end

When I run this, I get a Thread that tell me there is a NPE because $ea is
null... So I had to re-write that same rule as

rule "activate operations, for operator"
	when
		$worker : VCMShiftWorker( selectQuery == "operatorSelect" )
		$ea : ExecutableAction(
			$prio : priority,
			$workTime : workTime,
			$critical : critical,
			action.subject.parentActionable != null,
			$worker.isUnderManagement( action.subject.parentActionable )
		)
		not RelevantExecutableAction(
			$worker;
			executableAction != $ea,
			executableAction.priority > $priority ||
			(executableAction.priority == $priority &&
executableAction.workTime.compareTo($workTime) > 0) ||
			(executableAction.priority == $priority && executableAction.workTime ==
$workTime && $critical && ! executableAction.critical)
		)		
	then
		System.out.println($worker+" makes relevant :"+$ea);
		insert( new RelevantExecutableAction( $worker, $ea ) );
end

This works, but it's not nice.. And: why?

Also, I get errors like "java.lang.RuntimeException: Null accessor on node:
tick", again from these separate threads. I think this means that MVEL
cannot determine a getTick() from the fact that it should look at. In this
case, this.tick does also not work; same thing.

I tried to switch JIT off by adding the -Dmvel.disable.jit=true property to
the start-up, but that does not eliminate this issue.

A full stack-trace for the last error is as follows:

java.lang.RuntimeException: Null accessor on node: tick
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeNode(ConditionAnalyzer.java:229)
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeNode(ConditionAnalyzer.java:162)
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeSingleCondition(ConditionAnalyzer.java:109)
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeCondition(ConditionAnalyzer.java:102)
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeCombinedCondition(ConditionAnalyzer.java:134)
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeCondition(ConditionAnalyzer.java:94)
	at
org.drools.rule.constraint.ConditionAnalyzer.analyzeCondition(ConditionAnalyzer.java:73)
	at
org.drools.rule.constraint.MvelConditionEvaluator.getAnalyzedCondition(MvelConditionEvaluator.java:83)
	at
org.drools.rule.constraint.MvelConstraint.executeJitting(MvelConstraint.java:214)
	at
org.drools.rule.constraint.MvelConstraint.access$000(MvelConstraint.java:41)
	at org.drools.rule.constraint.MvelConstraint$1.run(MvelConstraint.java:201)
	at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:722)

Another thing that fails to work in 5.4 is casting. For instance:
((Ship)mover).currentContainer does not compute. I get a Null accessor on
mover...

Should I worry about this at all? Or is it just bad luck this time and will
Drools just continue to process my rules?

To give you some context. We have built an agent based simulation engine,
where the agents are "Smart". They can interact, responding to the Actions
published by the agents in their environment by reasoning over them using
Drools rules. Works really nice but I am getting worried by these exceptions
now...



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