[wildfly-dev] duel between JPA use of ClassFileTransformer and CDI implicit/explicit Bean Manager (why can't we just get along)...

[Jason Greene]

I haven't reviewed the JPA spec changes but don't entity listeners fire on instantiation or association and not during instrumentation? If so then it seems like there shouldn't be a problem?

The new rules say that CDI, by default, scans only classes which have been annotated as having a scope or an EE component that has a scope. So at least entities would normally be excluded. If someone does set an attribute in beans.xml to scan all resources then it definitely would attempt to load them. At some point we should update Weld to do more up front scanning before loading (it might already do some of that). Although I don't think this is the solution, it's just something I felt like noting.



On Jun 7, 2013, at 11:19 AM, Scott Marlow <smarlow at redhat.com> wrote:

> For application deployments that use ClassFileTransformer to 
> enhance/rewrite entity classes, we start the persistence unit service 
> (PersistenceProvider.createContainerEntityManagerFactory()) during the 
> Phase.FIRST_MODULE_USE (before any application classes have been loaded).
> 
> For application deployments that have an explicit CDI Bean Manager, 
> there is a beans.xml that means the ClassFileTransformer will not work, 
> since the CDI Bean Manager will scan all of the application classes 
> (loading them), before the persistence unit service is started (so that 
> the persistence provider can use CDI in entity listeners).
> 
> The same is also true for implicit CDI Bean manager support [1], expect 
> all application deployments that contain an ejb3 module, will be wired 
> for CDI (meaning JPA ClassFileTransformer support will work even less).
> 
> I raised this on the JPA 2.1 EG [2] in response to an earlier 
> discussion, about switching to a two phase approach to address problems 
> like this (didn't discuss CDI implicit support then but am raising that 
> now).
> 
> [3] talks about why we don't create the CDI bean managers before the 
> Install phase (would cause all application classes to be read which 
> breaks JPA ClassFileTransformer use).
> 
> [4] is for adding implicit CDI support but is blocked currently by [5].
> 
> We can add persistence unit flags (jboss.as.jpa.classtransformer=false) 
> for disabling JPA ClassFileTransformer support as a workaround but that 
> doesn't help enough since many deployments will have implicit CDI 
> support enabled (since they contain EJB modules).  We could add a way to 
> disable implicit CDI support as another workaround for deployments that 
> want to use ClassFileTransformer.
> 
> I'm not yet seeing a proper fix for this.  Anyone else?
> 
> Scott
> 
> [1] http://docs.jboss.org/cdi/spec/1.1/cdi-spec.html#bean_archive
> [2] 
> https://java.net/projects/jpa-spec/lists/jsr338-experts/archive/2013-06/message/0
> [3] https://issues.jboss.org/browse/WFLY-1322
> [4] https://issues.jboss.org/browse/WFLY-476
> [5] https://issues.jboss.org/browse/WFLY-1463
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