[rules-users] java.lang.LinkageError

Winfried wumb at gameduell.de
Wed Aug 22 11:29:36 EDT 2012 

We experience exactly the same behaviour/exceptions. I can reproduce 
this with following pattern:

1. Deploy application to Glassfish -> KnowledgeBase gets initialized 
from a .drl file and hold in a singleton
2. Run a multithreaded client sending requests to the application. Each 
request creates a stateful session out of the KnowledgeBase
3. The reported exceptions are thrown

Everything runs fine when sending a single initial request before 
running the multithreaded client.

Regarding compilation environment: Everything is compiled and runs on a 
single machine, i can assure there is only one java version involved.

For me this also looks like a multithreaded class loading issue as 
mentioned by David.



  Our rules are not precompiled

On 08/20/2012 10:00 PM, David Minor wrote:
> We've managed to determine that the problem only happens *sometimes*
> when the rule base is deserialized. Our current theory is that it's a
> multithreaded class loading issue, although our synchronization
> attempts haven't mitigated it.
>
> We've also seen this variation on the linkage error:
>
> Caused by: java.lang.LinkageError: loader (instance of
> org/drools/rule/JavaDialectRuntimeData$PackageClassLoader): attempted
> duplicate class definition for name:
> "ShoppingCart/Rule_CSPATCHARES5211_CSPATCHARES5211_dd9600d3d08d460caa50fe7c29ee5585"
>          at java.lang.ClassLoader.defineClass1(Native Method)
>          at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
>          at org.drools.rule.JavaDialectRuntimeData$PackageClassLoader.fastFindClass(JavaDialectRuntimeData.java:615)
>          at org.drools.util.CompositeClassLoader$CachingLoader.load(CompositeClassLoader.java:254)
>          at org.drools.util.CompositeClassLoader$CachingLoader.load(CompositeClassLoader.java:237)
>          at org.drools.util.CompositeClassLoader.loadClass(CompositeClassLoader.java:88)
>          at java.lang.ClassLoader.loadClass(ClassLoader.java:410)
>          at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
>          at ShoppingCart.Rule_CSPATCHARES5211_CSPATCHARES5211_dd9600d3d08d460caa50fe7c29ee5585Eval0InvokerGenerated.evaluate(Unknown
> Source)
>          at ShoppingCart.Rule_CSPATCHARES5211_CSPATCHARES5211_dd9600d3d08d460caa50fe7c29ee5585Eval0Invoker.evaluate(Unknown
> Source)
>          at org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:114)
>          at org.drools.reteoo.EvalConditionNode.assertLeftTuple(EvalConditionNode.java:178)
> ...
>
> On Fri, Aug 17, 2012 at 9:37 AM, David Minor <daveminor at gmail.com> wrote:
>> The webapps are both running in the same instance of Tomcat.
>>
>> We're going to try to run a second instance of Tomcat on production
>> with the new version to see if we can replicate it.
>>
>> On Fri, Aug 17, 2012 at 8:33 AM, Wolfgang Laun <wolfgang.laun at gmail.com> wrote:
>>> On 17/08/2012, David Minor <daveminor at gmail.com> wrote:
>>>> That was the root error, the rest is just drools firing its rules.
>>>>
>>>> So does this mean there's some sort of incompatibility in the class
>>>> ShoppingCart/Rule_CSMEGBUL_b996907c25e3495a94b6b041c1c08c50? I assume
>>>> this is a class that's auto-generated by drools. Is it possible that
>>>> serializing the rule Package is leading to an incompatible class
>>>> definition?
>>> It does contain compiled Java code. So if the DRL/Java compilation
>>> environment compared to the deployment environment differs w.r.t. to
>>> JDK version, you're in for trouble.
>>> -W
>>>
>>>> On Thu, Aug 16, 2012 at 10:41 PM, Wolfgang Laun <wolfgang.laun at gmail.com>
>>>> wrote:
>>>>> Javadoc: Subclasses of LinkageError indicate that a class has some
>>>>> dependency on another class; however, the latter class has
>>>>> incompatibly changed after the compilation of the former class.
>>>>>
>>>>> Looks like some incompatibility between your development and
>>>>> deployment environment.
>>>>>
>>>>> Did you truncate any helpful message from the stack trace?
>>>>>
>>>>> -W
>>>>>
>>>>> On 17/08/2012, David Minor <daveminor at gmail.com> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> We're in the process of moving our web apps from Java 5 to Java 7 and
>>>>>> Drools 3 to Drools 5.4.0. Our rule base is compiled and serialized to
>>>>>> the db by one app, and read from the db and fired by another.
>>>>>>
>>>>>> Everything went fine during testing, but when we tried to switch to
>>>>>> production we got this when firing the rule base:
>>>>>>
>>>>>> Caused by: java.lang.LinkageError:
>>>>>> ShoppingCart/Rule_CSMEGBUL_b996907c25e3495a94b6b041c1c08c50
>>>>>>          at
>>>>>> ShoppingCart.Rule_CSMEGBUL_b996907c25e3495a94b6b041c1c08c50Eval0InvokerGenerated.evaluate(Unknown
>>>>>> Source)
>>>>>>          at
>>>>>> ShoppingCart.Rule_CSMEGBUL_b996907c25e3495a94b6b041c1c08c50Eval0Invoker.evaluate(Unknown
>>>>>> Source)
>>>>>>          at
>>>>>> org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:114)
>>>>>>          at
>>>>>> org.drools.reteoo.EvalConditionNode.assertLeftTuple(EvalConditionNode.java:178)
>>>>>> [snip]
>>>>>>
>>>>>> Does anyone have any ideas as to what might cause this?
>>>>>>
>>>>>> Here is the rule in question if that helps:
>>>>>>
>>>>>> rule "CSMEGBUL"
>>>>>>          salience -1
>>>>>>          agenda-group "SubtotalDependent"
>>>>>>          when
>>>>>>                  delegate: PromotionRuleDelegate ( )
>>>>>>                  cart: ShoppingCart ( )
>>>>>>                  eval (
>>>>>> delegate.checkDateRange("1181718000000","1497337200000") )
>>>>>>                  eval ( delegate.checkEnabled("false") )
>>>>>>                  eval ( delegate.cartHasPromoCode(cart, "CSMEGBUL") )
>>>>>>                  eval ( delegate.checkUsage(1,100027) )
>>>>>>          then
>>>>>>                  delegate.applyOrderDiscountAmount(cart, 100027, "10.0");
>>>>>>                  delegate.promoCodeApplied(cart, "CSMEGBUL");
>>>>>> end
>>>>>>
>>>>>>
>>>>>> --
>>>>>> _____________
>>>>>> David Minor
>>>>>> _______________________________________________
>>>>>> rules-users mailing list
>>>>>> rules-users at lists.jboss.org
>>>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>>>
>>>>> _______________________________________________
>>>>> rules-users mailing list
>>>>> rules-users at lists.jboss.org
>>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>
>>>>
>>>> --
>>>> _____________
>>>> David Minor
>>>> _______________________________________________
>>>> rules-users mailing list
>>>> rules-users at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>
>>> _______________________________________________
>>> rules-users mailing list
>>> rules-users at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>> --
>> _____________
>> David Minor
>
>


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Winfried Umbrath
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