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

Wed Jan 11 14:42:41 EST 2017

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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