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https://issues.apache.org/jira/browse/UIMA-5054?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15419468#comment-15419468
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Richard Eckart de Castilho commented on UIMA-5054:
--------------------------------------------------

I'm only using that the ability to set a custom classloader in the resource 
manager in order to sneak in the thread context classloader which I found to be 
necessary in various circumstances. Otherwise, more-or-less the default 
classloaders should be used... at least if ClassUtils.class was loaded through 
the same loader as the rest of the relevant classes. The isolation capability 
is there but should in the uimaFIT scenario in most cases not really have any 
effect.

A better solution would IMHO be for UIMA to generally take the context 
classloader into account and to remove this "hack". It's not like anybody 
forces anyone to set the context classloader. But if it is set, it's surely set 
for a good reason.

> JCas returning generic class instead of JCas cover class
> --------------------------------------------------------
>
>                 Key: UIMA-5054
>                 URL: https://issues.apache.org/jira/browse/UIMA-5054
>             Project: UIMA
>          Issue Type: Bug
>          Components: Collection Processing
>    Affects Versions: 2.8.1SDK
>            Reporter: Richard Eckart de Castilho
>             Fix For: 2.9.0SDK
>
>
> A DKPro Core user reported that when deploying an AE in a CPE 
> he was unable to access a JCas cover class in the 
> entityProcessComplete(...) CPE callback. See: 
> https://groups.google.com/d/msg/dkpro-core-user/-DtO5Ivnk9I/sjQAPPv1BwAJ
> {noformat}
>         public void entityProcessComplete(CAS cas, EntityProcessStatus 
> status) {
>             try {
>                 JCas jcas = cas.getJCas();
>                 // here getting a JCas cover class fails. Instead,
>                 // an AnnotationImpl is returned from the jcas.
>             } catch (CASException e) {
>                 e.printStackTrace();
>             }
>         }
> {noformat}
> The problem appears to be that the static CAS classloaders are restored
> *before* invoking the entityProcessComplete() callback (CPMEngine 3468):
> {noformat}
>       try {
>         if (null != cas)
>           ((CASImpl)cas).switchClassLoaderLockCas(statCL);
>         statCL.entityProcessComplete(cas, eps);
>       } finally {
>         if (null != cas) 
>           ((CASImpl)cas).restoreClassLoaderUnlockCas();
>       }
> {noformat}
> Is there any reason that the classloaders are switched out before invoking 
> the callback? If not, any objection if I change the code such that the 
> callback is invoked before the classloaders are switched out?
> {noformat}
> Thread [[Procesing Pipeline#7 Thread]::] (Suspended (breakpoint at line 1021 
> in CASImpl))     
>       CASImpl.setLocalFsGenerators(FSGenerator<FeatureStructure>[]) line: 
> 1021        
>       FSClassRegistry.swapInGeneratorsForClassLoader(ClassLoader, CASImpl) 
> line: 225  
>       JCasImpl.switchClassLoader(ClassLoader) line: 548       
>       CASImpl.switchClassLoader(ClassLoader) line: 4195       
>       CASImpl.switchClassLoaderLockCasCL(ClassLoader) line: 4183      
>       CASImpl.switchClassLoaderLockCas(Object) line: 4176     
>       CPMEngine.callEntityProcessCompleteWithCAS(StatusCallbackListener, CAS, 
> EntityProcessStatus) line: 3472 
>       ProcessingUnit.doNotifyListeners(Object, boolean, EntityProcessStatus) 
> line: 1650       
>       ProcessingUnit.notifyListeners(Object, boolean, EntityProcessStatus) 
> line: 1592 
>       ProcessingUnit.processNext(Object[], ProcessTrace) line: 917    
>       ProcessingUnit.run() line: 575  
> {noformat}



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