[rules-users] Drools 5.5 divide by 0 exception

[gboro54]

Could you expand upon why this is a poor practice? I assumed that if a part
of the pattern doesn't match the expression evaluation is terminated


laune wrote
> I can anticipate the answer where OP says that there is a constraint
> restricting argVolume to > 0. However, I don't think that independent
> constraints such as we see them in this rule are evaluated as if they
> were in a single logical expression, with Java semantics.
> 
> The seductive possibility of binding to a half-baked expression (i.e.,
> $ratio:(volumeAccumulations["total"]/consolidatdVolume.avgVolume))
> should be discarded. This value can safely be computed on the RHS
> where the denominator's  value being !=0 is asserted.
> 
> -W
> 
> On 01/11/2013, Stephen Masters <

> stephen.masters@

> > wrote:
>> Divide by zero exceptions usually occur when you try to divide by zero.
>>
>> So … first question … is consolidatdVolume.avgVolume ever zero?
>>
>>
>> On 1 Nov 2013, at 16:17, gboro54 <

> gboro54@

> > wrote:
>>
>>> I have rules like the following:
>>>
>>> rule "Add Baseline to Context if it does not exists exists or not
>>> greater
>>> then 0"
>>> 	no-loop true
>>> 	when
>>> 		$context:Context($id:id,baselineParticipation==null ||
>>> 				
>>> baselineParticipation.baselineRatio==null||baselineParticipation.baselineRatio==0)
>>> 	then
>>> 		modify($firm) {setBaselineParticipation(new
>>> BaselineParticipation($id,new
>>> BigDecimal(0.00485)))};
>>> 		
>>> end
>>>
>>> rule "Calculate Participation Ratio"
>>> 	no-loop true
>>> 	when
>>> 	
>>> $context:Context(consolidatdVolume!=null,consolidatdVolume.avgVolume>0,
>>> 				  
>>> volumeAccumulations["total"]!=null,volumeAccumulations["total"]>0,
>>> 				  
>>> $ratio:(volumeAccumulations["total"]/consolidatdVolume.avgVolume))
>>> 	then
>>> 		ConcurrentMap calculatedRatios=$firm.getCalculatedRatios();
>>> 		calculatedRatios.put("fparticipationRatio",new BigDecimal($ratio));
>>> 		modify($firm){setCalculatedRatios(calculatedRatios)};
>>> end
>>>
>>> Despite the checks I get the following exception and any insight into
>>> why
>>> would be great:
>>>
>>> Exception executing consequence for rule "Calculate Firm Participation
>>> Ratio" in com.nasdaq.rms.nq.status: java.lang.ArithmeticException: / by
>>> zero
>>> Exception executing consequence for rule "Calculate Firm Participation
>>> Ratio" in com.nasdaq.rms.nq.status: java.lang.ArithmeticException: / by
>>> zero
>>> 	at
>>> org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
>>> 	at
>>> org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1297)
>>> 	at
>>> org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1221)
>>> 	at
>>> org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1456)
>>> 	at
>>> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710)
>>> 	at
>>> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674)
>>> 	at
>>> org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230)
>>> 	at
>>> com.nasdaq.fq.rms.workflow.processor.rules.PerformanceStatusAssignmentProcessor.doWork(PerformanceStatusAssignmentProcessor.java:156)
>>> 	at
>>> com.ften.ssr.workqueue.WorkItemRunnable.run(WorkItemRunnable.java:48)
>>> 	at
>>> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>>> 	at
>>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>>> 	at java.lang.Thread.run(Thread.java:724)
>>> Caused by: java.lang.ArithmeticException: / by zero
>>> 	at ConditionEvaluatorda6271cf5a744b6bbdb9c717cae2edb7.evaluate(Unknown
>>> Source)
>>> 	at
>>> org.drools.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:200)
>>> 	at
>>> org.drools.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:157)
>>> 	at org.drools.reteoo.AlphaNode.modifyObject(AlphaNode.java:154)
>>> 	at
>>> org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateModifyObject(CompositeObjectSinkAdapter.java:507)
>>> 	at
>>> org.drools.reteoo.CompositeObjectSinkAdapter.propagateModifyObject(CompositeObjectSinkAdapter.java:432)
>>> 	at org.drools.reteoo.AlphaNode.modifyObject(AlphaNode.java:157)
>>> 	at
>>> org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateModifyObject(CompositeObjectSinkAdapter.java:507)
>>> 	at
>>> org.drools.reteoo.CompositeObjectSinkAdapter.propagateModifyObject(CompositeObjectSinkAdapter.java:432)
>>> 	at
>>> org.drools.reteoo.ObjectTypeNode.modifyObject(ObjectTypeNode.java:314)
>>> 	at
>>> org.drools.reteoo.EntryPointNode.modifyObject(EntryPointNode.java:265)
>>> 	at org.drools.common.NamedEntryPoint.update(NamedEntryPoint.java:483)
>>> 	at org.drools.common.NamedEntryPoint.update(NamedEntryPoint.java:383)
>>> 	at
>>> org.drools.base.DefaultKnowledgeHelper.update(DefaultKnowledgeHelper.java:337)
>>> 	at
>>> com.nasdaq.rms.nq.status.Rule_Calculate_Firm_Participation_Ratio_cfb033f33c2b404fb2bff8e1b9af0175.defaultConsequence(Unknown
>>> Source)
>>> 	at
>>> com.nasdaq.rms.nq.status.Rule_Calculate_Firm_Participation_Ratio_cfb033f33c2b404fb2bff8e1b9af0175DefaultConsequenceInvokerGenerated.evaluate(Unknown
>>> Source)
>>> 	at
>>> com.nasdaq.rms.nq.status.Rule_Calculate_Firm_Participation_Ratio_cfb033f33c2b404fb2bff8e1b9af0175DefaultConsequenceInvoker.evaluate(Unknown
>>> Source)
>>> 	at
>>> org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1287)
>>> 	... 10 more
>>>
>>>
>>>
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