Barath,

   What version of drools are you using?

   The drools rulebase is designed to be shared among multiple threads. The working memory (session) is not.
   Having said that, we had a couple bugs in the past regarding multi-thread environments, and so you must use 4.0.7 version that is about to be released. For you test, while you wait for the official release, you can checkout the code and built it from here:

http://anonsvn.labs.jboss.com/labs/jbossrules/branches/4.0.x/

   []s
   Edson

2008/5/5 Barath <barathguna@gmail.com>:

Hi,

While doing a load test with jmeter,my web service application with drools
works fine for few clients(5 simultaneous hits for 10 times)
but when i increase my clients(120 simultanious hits for 100 times) i am
gettin the following exception for
few client, (out of 12,000 hits 200 throws this exception)

problem encountered at node [11] 5{170,189}: unable to resolve property:
null pointer exception in property: declr.identifier
org.mvel.TemplateInterpreter.execute(TemplateInterpreter.java:528)
org.mvel.TemplateInterpreter.parse(TemplateInterpreter.java:341)
org.drools.rule.builder.dialect.java.AbstractJavaBuilder.generatTemplates(AbstractJavaBuilder.java:113)
org.drools.rule.builder.dialect.java.JavaConsequenceBuilder.build(JavaConsequenceBuilder.java:95)
org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:67)
org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:446)
org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:304)
org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:167)
com.drools.util.RuleEngine.applyRule(RuleEngine.java:47)
com.drools.util.DroolsController.getAdvertisement(DroolsController.java:94)
com.drools.util.DroolsController.routeBusinessMethod(DroolsController.java:67)
com.drools.util.DroolsController.getAdvertisement(DroolsController.java:43)
com.drools.MyEndpoint.getAdvertisement(MyEndpoint.java:237)
com.drools.MyEndpoint.process(MyEndpoint.java:144)
org.apache.servicemix.common.AsyncBaseLifeCycle.doProcess(AsyncBaseLifeCycle.java:489)
org.apache.servicemix.common.AsyncBaseLifeCycle.processExchange(AsyncBaseLifeCycle.java:441)
org.apache.servicemix.common.BaseLifeCycle.onMessageExchange(BaseLifeCycle.java:46)
org.apache.servicemix.jbi.messaging.DeliveryChannelImpl.processInBound(DeliveryChannelImpl.java:595)
org.apache.servicemix.jbi.nmr.flow.AbstractFlow.doRouting(AbstractFlow.java:174)
org.apache.servicemix.jbi.nmr.flow.seda.SedaFlow.doRouting(SedaFlow.java:176)
org.apache.servicemix.jbi.nmr.flow.seda.SedaQueue$1.run(SedaQueue.java:134)
edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:665)
edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:690)
java.lang.Thread.run(Thread.java:619)

drl file has 6 rules,
5 rules                   - which retract facts which passes the rule.
1 rule(low salience)  - will add the fact to java.util.List (set as global)
which passes the rule.

1 . Am i getting this error bcoz of the global list? or any other reason?
2 . How to solve this problem?

here the rules,

<code>
global java.util.List feasibleAdv;

rule " percentage rule "
   when
       $adv : Advertisement( percentageLimit != 0 , percentageLimit <
playedPercentage )
   then
       System.out.println("remove this adv (failed percentage):
"+$adv.getAdvertisementID());
       retract($adv);
end

rule "per day rule"
   when
       $adv : Advertisement( limitperday != 0 , limitperday <= playedperday
)
   then
       //System.out.println("remove this adv (failed day):
"+$adv.getAdvertisementID());
       retract($adv);
end

rule "per week rule"
   when
       $adv : Advertisement( limitperweek != 0 , limitperweek <=
playedperweek)
   then
       //System.out.println("remove this adv (failed week):
"+$adv.getAdvertisementID());
       retract($adv);
end

rule "per month rule"
   when
       $adv : Advertisement( limitpermonth != 0 , limitpermonth <=
playedpermonth)
   then
       //System.out.println("remove this adv (failed month) :
"+$adv.getAdvertisementID());
       retract($adv);
end

rule "total played rule"
   when
       $adv : Advertisement( totallimit != 0 , totallimit <= totalplayed )
   then
       //System.out.println("remove this adv (failed total played) :
"+$adv.getAdvertisementID());
       retract($adv);
end


rule "advertisement select rule"
salience -1
       when
               $adv : Advertisement( $playedPercentPerAdvertisement :
playedPercentPerAdvertisement)
               not( Advertisement( playedPercentPerAdvertisement <
$playedPercentPerAdvertisement ) )
               $advertisementCount : Integer()
       then
               boolean status = true;
               if($advertisementCount-1 < 0){
                       //System.out.println("halted");
                       status = false;
                       drools.halt();
               }
               if(status){
                       feasibleAdv.add($adv);
                       drools.update(
drools.getWorkingMemory().getFactHandle($advertisementCount), new
Integer($advertisementCount-1) );
                       retract($adv);
               }
end

</code>
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--
Edson Tirelli
JBoss Drools Core Development
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
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