[rules-users] Memory leak due CompositeClassLoader

[Mark Proctor]

Se the currentContext ClassLoader to null, when initialising the knowledge base. Then reset it after you are done.

Mark
On 2 Apr 2014, at 08:04, Romain Thouvenin <romain.thouvenin at amadeus.com> wrote:

> Before asking for an upgrade to this third party, I did a test. 
> I managed to assemble a build of the component using Drools 5.6.0.Final, and tried to use-and-redeploy my webapp. 
> 
> I did not face any problem due to the upgrade, but it seems the leak is still there. 
> Out of the two instances of CompositeClassLoader that I could see with 5.2.1, one has gone so it is going in the good direction. 
> But there is still one that prevents garbage collection. 
> 
> The CompositeClassLoader is given the webapp class loader instance when it is instantiated by RuleBaseConfiguration: 
> 
>    ClassLoaderUtil.getClassLoader(ClassLoader[], Class<?>, boolean) line: 43         
>    at RuleBaseConfiguration.setClassLoader(ClassLoader...) line: 945         
>    at RuleBaseConfiguration.init(Properties, ClassLoader...) line: 421         
>    at RuleBaseConfiguration.<init>() line: 267         
>    at RuleBaseConfiguration.<clinit>() line: 175         
> 
> 
> Any work-around available in 5.6? 
> 
> Thanks, 
> Romain 
> 
> 
> 
> 
> 
> From:        Mark Proctor <mproctor at codehaus.org> 
> To:        Rules Users List <rules-users at lists.jboss.org>, 
> Date:        01/04/2014 19:38 
> Subject:        Re: [rules-users] Memory leak due CompositeClassLoader 
> Sent by:        rules-users-bounces at lists.jboss.org 
> 
> 
> 
> There were a lot of fixes around this and other areas. Please upgrade to 5.6, then come back if you have problems. 
> 
> Mark 
> On 1 Apr 2014, at 14:24, Romain Thouvenin <romain.thouvenin at amadeus.com> wrote: 
> 
> Hello, 
> 
> I am working on a Web application that uses a third-party component that uses Drools 5.2.1 (I know this is old, but this is not my choice). 
> While investigating memory leaks in my application, I found out that after redeploying the webapp in the application server (Weblogic), the leaking class loader is referenced by: 
> 
>   org.drools.util.CompositeClassLoader.classLoaders 
> 
> This is because when that class is instantiated by org.drools.util.ClassLoaderUtil, the initial list of class loaders includes the context class loader of the current thread, which is the class loader of my webapp. But the class loader of CompositeClassLoader is not the same as my webapp, so when I redeploy my webapp CompositeClassLoader continues to exist and keep that reference to the webapp class loader, which is therefore never garbage-collected. 
> 
> Browsing a bit through the code, I see no reference to CompositeClassLoader.removeClassLoader that could remove the faulty reference. 
> 
> So my questions are: 
> 1) Is my investigation correct? 
> 
> 2) I found this thread on the list: http://drools.46999.n3.nabble.com/permgen-leak-td4027038i20.html 
> Is this the same issue as mine, meaning that it is fixed in 5.6.0 and 6.0? 
> If yes, pushing this third-party component to upgrade is really the only solution I have? 
> 
> I am not at all a knowledgeable user of drools, I just happen to be user of that third-party component, that is why I wanted confirmation of my findings. 
> 
> Thanks for your help! 
> Romain 
> 
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