[hibernate-dev] Javassist enhancement problems with the Hibernate ORM WildFly modules

[Steve Ebersole]

To be clear... ORM is "expecting the application classpath to include
Javassist dependency" because it will need it for the *proxies* Hibernate
returns to be usable once they get them from Hibernate.

It may or may not *need* the application classpath to include Javassist
dependency if the application is using bytecode generation and *not
proxies*.  I have not played with this specifically.

On the bytecode generation side I am pretty sure Rafeal said Byte Buddy
would not be needed on the application's classpath.  No idea about
proxies.  Just in general I think generated proxies are always going to
need the underlying library available.

On Thu, Jan 12, 2017, 8:36 AM Scott Marlow <smarlow at redhat.com> wrote:

No, not currently.  We created
https://github.com/wildfly/wildfly/pull/8474 to move the exporting of
Javassist, to the WildFly static ORM module, so that Hibernate native
applications would automatically get the Javassist classes.  That
wouldn't of directly addressed your situation but it would of updated
the WildFly JPA container (JPADependencyProcessor class) to no longer
do the javassist export, so you would of had more control.  I don't
think that https://github.com/wildfly/wildfly/pull/8474 is likely to
be merged.  Instead, ORM needs to stop expecting the application
classpath  to include Javassist dependency and then we can update
JPADependencyProcessor to stop exporting Javassist.

Perhaps we could discuss this in person soon, to see if we are all on
the same page.  My current understanding is that this will be
addressed when we switch to Byte Buddy, but the shading (Javassist)
idea may also help, as we could stop exporting Javassist from the
WildFly JPA container.


On Thu, Jan 12, 2017 at 7:36 AM, Sanne Grinovero <sanne at hibernate.org>
wrote:
> Following Steve's suggestions I thought I had a reasonable and clean
> plan, but it's not working in practice.
>
> Turns out that even after me cleaning up all references to
> "org.javassist:main", it's still been forced on the classpath by
> hard-coded rules in the JPADependencyProcessor, so conflicting with
> the right version:
>  -
https://github.com/wildfly/wildfly/blob/6b61a6003f704221f66dcd9f418bcb7af88fb9ab/jpa/subsystem/src/main/java/org/jboss/as/jpa/processor/JPADependencyProcessor.java#L95
>
> Is there any way I can prevent this injection from happening? Can I
> override this JPADependencyProcessor?
>
> Thanks,
> Sanne
>
> On 11 January 2017 at 19:42, Scott Marlow <smarlow at redhat.com> wrote:
>> I'm not really sure but did notice that HikariCP [1] shaded the
>> Javassist runtime classes in 2015 and still seems to be shading
>> Javassist.
>>
>> Good point about about the compatibility impact, as build time
>> instrumentation with the non-shaded Javassist will produce a Java
>> archive that doesn't work with the shaded Javassist.  The application
>> will get a CNFE exception unless they add a dependency on the unshaded
>> Javassist classes.  I would expect the same problem when we change
>> from using Javassist to using Byte Buddy.
>>
>> [1]
https://github.com/brettwooldridge/HikariCP/search?utf8=%E2%9C%93&q=javassist
>>
>> On Wed, Jan 11, 2017 at 11:48 AM, Emmanuel Bernard
>> <emmanuel at hibernate.org> wrote:
>>> The one small issue is that if the user enhanced the classes at build
time (i,e. not via the ClassTransformer), then shading in a newer version
of Wildfly means that the same app using the later version will fail unless
you rebuild the app.
>>> BTW is Javassist Shadable, some of these libs can’t due to string
referencing classnames and other fun tricks like that.
>>>
>>> Emmanuel
>>>
>>>> On 11 Jan 2017, at 17:35, Scott Marlow <smarlow at redhat.com> wrote:
>>>>
>>>> On Wed, Jan 11, 2017 at 11:19 AM, Steve Ebersole <steve at hibernate.org>
wrote:
>>>>> I think the best option in terms of supporting legacy ORM version
users
>>>>> would be to incorporate a change in those branches to shade/shadow
Javassist
>>>>> into ORM specific packages (in hibernate-core).
>>>>
>>>> +1
>>>>
>>>>>
>>>>> As I understand it, it is always ORM that does the enhancement, right
Scott?
>>>>
>>>> Yes, ORM always does the enhancement.
>>>>
>>>>>
>>>>> On Wed, Jan 11, 2017 at 10:12 AM Scott Marlow <smarlow at redhat.com>
wrote:
>>>>>>
>>>>>> Ahh, I was confused then, your talking about the WildFly ORM static
>>>>>> module definition [1], which is not controlled by the JPA container
or
>>>>>> JipiJapa.
>>>>>>
>>>>>>>>
>>>>>>>> We talked about this not long ago and possible solutions, the only
>>>>>>>> agreed on solution was to eliminate the ORM requirement for
Javassist
>>>>>>>> classes to be on the application classpath, by switching to
ByteBuddy.
>>>>>>>
>>>>>>> Like I replied to Gunnar, that's a different problem. Sorry all for
>>>>>>> the confusion!
>>>>>>>
>>>>>>> In this case it's Hibernate ORM which is being fed two different
>>>>>>> versions of Javassist simultaneously; clearly that's our fault. The
>>>>>>> application classpath is not affected.
>>>>>>>
>>>>>>>> Could you could use one of the previously suggested solutions in
your
>>>>>>>> testing?  For example, your application could use a shaded
Javassist
>>>>>>>> jar, that doesn't interfere with the ORM Javassist.
>>>>>>>
>>>>>>> I'm not trying to use Javassist. If only the flags to disable it
would
>>>>>>> work I'd be happy to disable it ;-)
>>>>>>
>>>>>> There are no flags for controlling [1], if you want control, just
fork
>>>>>> WildFly and make occasional changes to the static module definitions
>>>>>> that meet your testing changes.  Just keep the changes as minimal as
>>>>>> possible, so it is easy to sync up the (test purposes) fork.  The
>>>>>> painful part though might be trying to push your fork to maven, so
>>>>>> perhaps this is a bad idea, but still wanted to mention it, in case
it
>>>>>> could help.
>>>>>>
>>>>>>>>
>>>>>>>> Why don't you contribute code changes instead to WildFly?  I did
>>>>>>>> create a pull request for https://issues.jboss.org/browse/WFLY-5773
>>>>>>>> that is still pending, to remove some unneeded dependencies.  This
>>>>>>>> won't get merged without an EAP jira that goes with it, which I
don't
>>>>>>>> plan to create, since there is no EAP need for the change.  Pull
>>>>>>>> request is https://github.com/wildfly/wildfly/pull/9305.
>>>>>>>
>>>>>>> Thanks! Sure I'd be happy to contribute these to WildFly, but
knowing
>>>>>>> which dependency is needed - or MIGHT be needed in certain
>>>>>>> configurations - requires in depth knowledge of the module one wants
>>>>>>> to cleanup.
>>>>>>
>>>>>> I'm not sure how you could dynamically update the ORM static module
>>>>>> definition [1].
>>>>>>
>>>>>>> I just have the *impression* that some of these dependencies are no
>>>>>>> longer needed, but going back and forth between projects at
different
>>>>>>> releases - and supposed to support various other versions - doesn't
>>>>>>> make it easy.
>>>>>>
>>>>>> ORM definitely still needs the Javassist dependency, but we should
>>>>>> drop ASM, as that is not needed, as well as a few others.
>>>>>>
>>>>>>>
>>>>>>> So I suspect that if the adaptor code itself was bundled directly
with
>>>>>>> the consuming JPA implementor, this would come more natural? Just an
>>>>>>> idea.
>>>>>>
>>>>>> I agree, but others didn't when this came up on the JPA expert group
>>>>>> mailing list before.
>>>>>>
>>>>>>>
>>>>>>> See the problem is Hibernate Search needs to test with latest ORM
way
>>>>>>> more regularly, so I can't wait for PRs to be included in WildFly,
>>>>>>> even less so if they are on hold because of even slower EAP cycles.
>>>>>>
>>>>>> I agree that you really need control over the static ORM module
>>>>>> definitions.  If you don't want to fork WildFly for testing, perhaps
>>>>>> you could modify the static orm module definition before starting the
>>>>>> app server, for the testing.  Sounds like a pita.
>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>>> - we should hide Javassist & Byte Buddy from being exposed to the
>>>>>>>>> application
>>>>>>>>
>>>>>>>> Yes, I agree.  You said this before but its ORM that requires
>>>>>>>> Javassist classes to be on the application classpath.  ORM does not
>>>>>>>> require the Byte Buddy classes to be on the application classpath.
>>>>>>>>
>>>>>>>>> - make Byte Buddy an option: I guess improve the JipiJapa
itegration
>>>>>>>>> to support it and move it into its own private module.
>>>>>>>>
>>>>>>>> No, ORM doesn't require Byte Buddy to be on the application
classpath,
>>>>>>>> which means that Byte Buddy can be what you want, a separate
private
>>>>>>>> ORM module.  This is a feature of WildFly modules, not JipiJapa.
>>>>>>>
>>>>>>> What I mean is that JipiJapa is currently triggering enhancement via
>>>>>>> Javassist; it's not giving me an option to use Byte Buddy instead.
>>>>>>
>>>>>> Its more that the WildFly JPA container, allows the persistence
>>>>>> provider to register a javax.persistence.spi.ClassTransformer
>>>>>> instance, to be called when entity class definitions are loaded, as
>>>>>> per the JPA requirements.  JipiJapa doesn't get involved, as there is
>>>>>> a standard JPA contract that ORM uses, so JipiJapa couldn't influence
>>>>>> use of Byte Buddy or CGLIB or Javassist...
>>>>>>
>>>>>>>
>>>>>>> So since the sources for that are in yet another project, it looks
>>>>>>> like I'd need 6 months to finish my ORM upgrade in Search. Luckily
>>>>>>> I'll aim for a different solution ;)
>>>>>> :(
>>>>>>
>>>>>> Scott
>>>>>>
>>>>>> [1]
>>>>>>
https://github.com/wildfly/wildfly/blob/master/feature-pack/src/main/resources/modules/system/layers/base/org/hibernate/jipijapa-hibernate5/main/module.xml#L47
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