[jboss-jira] [JBoss JIRA] (JBRULES-3675) java.lang.LinkageError, but only sometimes (multithreading issue)

[Craig West (JIRA)]

    [ https://issues.jboss.org/browse/JBRULES-3675?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13100779#comment-13100779 ] 

Craig West commented on JBRULES-3675:
-------------------------------------

What is the status of this issue? I am a little confused that a couple of hours after the user reported that the proposed solution did not resolve the issue, this was marked as resolved.

> java.lang.LinkageError, but only sometimes (multithreading issue)
> -----------------------------------------------------------------
>
>                 Key: JBRULES-3675
>                 URL: https://issues.jboss.org/browse/JBRULES-3675
>             Project: JBRULES
>          Issue Type: Bug
>          Components: drools-core
>    Affects Versions: 5.4.0.Final
>         Environment: - JBoss 7.1.1
> - drools 5.4.0.Final
> - jdk 1.6u30
> - Windows 7 64 bit
>            Reporter: kenneth westelinck
>            Assignee: Mario Fusco
>             Fix For: 6.0.0.Alpha1
>
>
> See mail on mailinglist:
> {noformat}
> We have an application (A) deployed on JBoss 7.1.1 accepting commands (CQRS,
> but only C and Q :) ). A console application (B) is sending a large volume
> of commands to create entities in A. Entities in A are validated by Drools
> (plain drl files, configured in spring using drools-spring). Most of the
> time this works just fine. But sometimes, we get the following exception:
> java.lang.LinkageError: loader (instance of
> org/drools/rule/JavaDialectRuntimeData$PackageClassLoader): attempted
> duplicate class definition for name:
> "a/b/c/Rule_person_unique___name_656ee3db19d34e689d95e2d6b2be67b6"
>         at java.lang.ClassLoader.defineClass1(Native Method) [rt.jar:1.6.0_30]
>         at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) [rt.jar:1.6.0_30]
>         at java.lang.ClassLoader.defineClass(ClassLoader.java:615) [rt.jar:1.6.0_30]
>         at org.drools.rule.JavaDialectRuntimeData$PackageClassLoader.fastFindClass(JavaDialectRuntimeData.java:615) [drools-core-5.4.0.Final.jar:5.4.0.Final]
>         at org.drools.util.CompositeClassLoader$CachingLoader.load(CompositeClassLoader.java:254) [knowledge-api-5.4.0.Final.jar:5.4.0.Final]
>         at org.drools.util.CompositeClassLoader$CachingLoader.load(CompositeClassLoader.java:237) [knowledge-api-5.4.0.Final.jar:5.4.0.Final]
>         at org.drools.util.CompositeClassLoader.loadClass(CompositeClassLoader.java:88) [knowledge-api-5.4.0.Final.jar:5.4.0.Final]
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:295) [rt.jar:1.6.0_30]
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:247) [rt.jar:1.6.0_30]
>         at a.b.c.Rule_person___unique___name_656ee3db19d34e689d95e2d6b2be67b6Eval0InvokerGenerated.evaluate(Unknown Source)
>         at a.b.c.Rule_person___unique___name_656ee3db19d34e689d95e2d6b2be67b6Eval0Invoker.evaluate(Unknown Source)
>         at org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:114) [drools-core-5.4.0.Final.jar:5.4.0.Final]
> Any idea where this is coming from or what's causing this. 
> {noformat}
> And the answer:
> {noformat}
> I have never experienced this myself, but after having a quick look at the code I believe this could be a multi-threading problem.
> In the abstract class java.lang.ClassLoader the method loadClass(String, boolean) is synchronized, but both org.drools.util.CompositeClassLoader
> and org.drools.rule.JavaDialectRuntimeData$PackageClassLoader override this method without the use of "synchronized".
> I would suggest you create a JIRA issue for this.
> {noformat}
> We are now trying 5.5.0.CR1 and so far, we have not encountered this issue. I'll keep you posted should the same issue appear on 5.5.0.CR1



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