RFR 8145964: NoClassDefFound error in transforming lambdas
Coleen Phillimore
coleen.phillimore at oracle.com
Thu Aug 18 21:30:15 UTC 2016
Thank you, Tom.
Coleen
On 8/18/16 1:31 PM, Tom Rodriguez wrote:
> Looks good to me.
>
> tom
>
>> On Aug 18, 2016, at 6:11 AM, Coleen Phillimore <coleen.phillimore at oracle.com> wrote:
>>
>>
>> New webrev:
>>
>> http://cr.openjdk.java.net/~coleenp/8145964.05/webrev
>>
>> I changed the wording as Dan suggested, see:
>>
>> http://cr.openjdk.java.net/~coleenp/jvmti.html#IsModifiableClass
>>
>> I also added the wording in CFLH to except anonymous classes.
>>
>> http://cr.openjdk.java.net/~coleenp/jvmti.html#ClassFileLoadHook
>>
>> I think I have no typos... I checked this a bunch of times.
>>
>> Thanks,
>> Coleen
>>
>>
>> On 8/18/16 8:36 AM, Coleen Phillimore wrote:
>>>
>>> On 8/17/16 9:39 PM, Daniel D. Daugherty wrote:
>>>> On 8/16/16 5:16 PM, Coleen Phillimore wrote:
>>>>>
>>>>> On 8/15/16 10:01 PM, David Holmes wrote:
>>>>>> On 16/08/2016 9:34 AM, Coleen Phillimore wrote:
>>>>>>> Rereading this and looking at the JVMTI spec, I think Dan's wording and
>>>>>>> changes make the most sense, if we are to keep IsModifiableClass to
>>>>>>> exclude retransforming classes, with the exception of specifying
>>>>>>> anonymous classes. I think the wording should just say "some
>>>>>>> implementation defined classes" as below.
>>>>>> I'm not sure what you mean exactly. Dan's changes seemed excessive to me. The only changes I see as essential are expressing the can_redefine/restransform_* in terms of IsModifiableClass.
>>>>> David, I did three things. I changed the description for the capabilities can_redefine_any_class and can_retransform_any_class to:
>>>>>
>>>>> http://cr.openjdk.java.net/~coleenp/jvmti.html#jvmtiCapabilities.can_redefine_any_class
>>>> Formatting looks good to me.
>>>>
>>>>
>>>>> http://cr.openjdk.java.net/~coleenp/jvmti.html#jvmtiCapabilities.can_retransform_any_class
>>>> Formatting looks good to me
>>>>
>>>>
>>>>> And added "some implementation defined classes" to the description of IsModifiableClass
>>>>>
>>>>> http://cr.openjdk.java.net/~coleenp/jvmti.html#IsModifiableClass
>>>> Formatting looks good to me.
>>>>
>>>>
>>>>> I also rewrote the test. See webrev:
>>>>>
>>>>> http://cr.openjdk.java.net/~coleenp/8145964.04/webrev/index.html
>>>> src/share/vm/prims/jvmti.xml
>>>> L7161: <capability id="can_redefine_any_class">
>>>> L7162: If possessed then all classes (except primitive, array, and some implementation defined
>>>> L7163: classes) are modifiable.
>>>>
>>>> L7163 should be:
>>>>
>>>> classes) are modifiable (redefine or retransform).
>>>>
>>>> The above change matches the style used in can_redefine_any_class
>>>> entry in the capability table.
>>> Okay, I added this.
>>>
>>>> L7165: <capability id="can_retransform_any_class">
>>>> L7166: If possessed then all classes (except primitive, array, and some implementation defined
>>>> L7167: classes) are modifiable.
>>>>
>>>> L7167: should be:
>>>>
>>>> classes) are modifiable with <functionlink id="RetransformClasses"/>.
>>>>
>>> Okay, I added this also.
>>>
>>>> The above change matches the style used in can_retransform_any_class
>>>> entry in the capability table.
>>>>
>>>> The two _any_ capability entries are written in different styles
>>>> because they were added at different times possibly by different
>>>> people...
>>> Yes, I left them inconsistent in the capability table because that's the way it was and it's not obvious whether that's correct or not.
>>>> src/share/vm/prims/jvmtiEnv.cpp
>>>> No comments.
>>>>
>>>> src/share/vm/prims/jvmtiRedefineClasses.cpp
>>>> No comments.
>>>>
>>>> test/runtime/RedefineTests/RetransformAnonymous.java
>>>>
>>>> Since the test now does both retransform and redefine operations,
>>>> you should rename it to ModifyAnonymous.java.
>>> Sure.
>>>
>>>> L59: static boolean done = false;
>>>> This should be a volatile since it's used by two threads.
>>>>
>>> Okay, fixed.
>>>
>>>
>>> Thank you for the careful review and thought and all the background information about this issue.
>>>
>>> Coleen
>>>
>>>> Dan
>>>>
>>>>
>>>>> What do you think?
>>>>>
>>>>> Thanks,
>>>>> Coleen
>>>>>
>>>>>> David
>>>>>>
>>>>>>> thanks,
>>>>>>> Coleen
>>>>>>>
>>>>>>> On 8/14/16 10:20 PM, Daniel D. Daugherty wrote:
>>>>>>>> On 8/12/16 6:33 PM, Coleen Phillimore wrote:
>>>>>>>>>
>>>>>>>>> On 8/12/16 7:51 PM, David Holmes wrote:
>>>>>>>>>> Hi Coleen,
>>>>>>>>>>
>>>>>>>>>> On 13/08/2016 4:19 AM, Coleen Phillimore wrote:
>>>>>>>>>>> Okay, I've made retransforming a class an unmodifiable class error and
>>>>>>>>>>> will give whoever complains your phone number. I've run the change
>>>>>>>>>>> through the redefinition tests in our colocated (our closed),
>>>>>>>>>>> noncolocated (also oracle-only), jdk/test/java/lang/instrument and
>>>>>>>>>>> jdk/test/com/sun/jdi testsets.
>>>>>>>>>>>
>>>>>>>>>>> Please see new webrev.
>>>>>>>>>>>
>>>>>>>>>>> http://cr.openjdk.java.net/~coleenp/8145964.03/webrev/index.html
>>>>>>>>>> Thanks, this is my preferred solution.
>>>>>>>>>>
>>>>>>>>>> Nit:
>>>>>>>>>>
>>>>>>>>>> ! // Cannot redefine an anonymous class. Retransform filters them
>>>>>>>>>> out.
>>>>>>>>>>
>>>>>>>>>> The second sentence is not needed now.
>>>>>>>>> Thanks, David. HIt reload, I had already changed that sentence but
>>>>>>>>> neglected to create a new webrev.
>>>>>>>>>> I didn't fully grok the test as I'm not familiar the various pieces.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> You need a second reviewer anyway so hopefully John and Tom will
>>>>>>>>>> still chime in.
>>>>>>>>> Okay, I'll wait but it would be nice for someone else on the team to
>>>>>>>>> review.
>>>>>>>>> http://cr.openjdk.java.net/~coleenp/8145964.03/webrev/index.html
>>>>>>>> src/share/vm/prims/jvmtiEnv.cpp
>>>>>>>> No comments.
>>>>>>>>
>>>>>>>> src/share/vm/prims/jvmtiRedefineClasses.cpp
>>>>>>>> L133: // classes for primitives and arrays cannot be redefined
>>>>>>>> That comment needs updating.
>>>>>>>>
>>>>>>>> test/runtime/RedefineTests/RetransformAnonymous.java
>>>>>>>> L39: why is there a blank line here (in the middle of the imports)?
>>>>>>>>
>>>>>>>> L79: System.out.println("retransform called for " + name);
>>>>>>>> Perhaps add "unexpected" to that message?
>>>>>>>>
>>>>>>>> Shouldn't there also be a test for RedefineClasses()?
>>>>>>>>
>>>>>>>>
>>>>>>>> The JVM/TI spec will need updates also:
>>>>>>>>
>>>>>>>> - RedefineClasses() API
>>>>>>>> - RetransformClasses() API
>>>>>>>> - IsModifiableClass() API
>>>>>>>>
>>>>>>>> Here's the line from IsModifiableClass():
>>>>>>>>
>>>>>>>>> Primitive classes (for example, java.lang.Integer.TYPE) and array
>>>>>>>> classes are never modifiable.
>>>>>>>>
>>>>>>>> Perhaps change it like this:
>>>>>>>>
>>>>>>>> Primitive classes (for example, java.lang.Integer.TYPE), array
>>>>>>>> classes, and
>>>>>>>> some implementation defined classes (for example, anonymous classes)
>>>>>>>> are
>>>>>>>> never modifiable.
>>>>>>>>
>>>>>>>> Similar wording changes should be done for RedefineClasses() and
>>>>>>>> RetransformClasses() APIs.
>>>>>>>>
>>>>>>>> There are various places that refer to can_redefine_any_class. Those
>>>>>>>> places
>>>>>>>> also need updating. Here's the one from RedefineClasses:
>>>>>>>>
>>>>>>>>> can_redefine_any_class Can modify (retransform or redefine) any
>>>>>>>> non-primitive
>>>>>>>>> non-array class. See IsModifiableClass.
>>>>>>>> Should probably be changed to something like:
>>>>>>>>
>>>>>>>> can_redefine_any_class Can modify (retransform or redefine) any
>>>>>>>> class except for
>>>>>>>> a few specific classes. See
>>>>>>>> IsModifiableClass for the classes
>>>>>>>> that cannot be modified.
>>>>>>>>
>>>>>>>> Similar wording change in the jvmtiCapabilities table that lists
>>>>>>>> can_redefine_any_class. Of course, IsModifiableClass itself will
>>>>>>>> have to be updated to spell out the classes that can't be modified.
>>>>>>>>
>>>>>>>> Looks like the spec wording for can_retransform_any_class is pretty
>>>>>>>> much wrong w.r.t. IsModifiableClass() stuff and will all need work.
>>>>>>>> Also looks like can_retransform_any_class wording is completely
>>>>>>>> missing from IsModifiableClass().
>>>>>>>>
>>>>>>>> Sorry this is turning into a can of worms...
>>>>>>>>
>>>>>>>> Dan
>>>>>>>>
>>>>>>>>
>>>>>>>>> thanks,
>>>>>>>>> Coleen
>>>>>>>>>> Thanks,
>>>>>>>>>> David
>>>>>>>>>>
>>>>>>>>>>> Thanks,
>>>>>>>>>>> Coleen
>>>>>>>>>>>
>>>>>>>>>>> On 8/11/16 11:44 PM, David Holmes wrote:
>>>>>>>>>>>> On 12/08/2016 12:23 AM, Coleen Phillimore wrote:
>>>>>>>>>>>>> On 8/11/16 8:20 AM, David Holmes wrote:
>>>>>>>>>>>>>> On 11/08/2016 10:09 PM, Coleen Phillimore wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On 8/10/16 8:37 PM, David Holmes wrote:
>>>>>>>>>>>>>>>> Hi Coleen,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> On 11/08/2016 12:45 AM, Coleen Phillimore wrote:
>>>>>>>>>>>>>>>>> New webrev:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> http://cr.openjdk.java.net/~coleenp/8145964.02/webrev/index.html
>>>>>>>>>>>>>>>> First I'm very surprised that the existing logic in
>>>>>>>>>>>>>>>> JvmtiEnv::RetransformClasses doesn't utilize
>>>>>>>>>>>>>>>> VM_RedefineClasses::is_modifiable_class to determine when to
>>>>>>>>>>>>>>>> return
>>>>>>>>>>>>>>>> JVMTI_ERROR_UNMODIFIABLE_CLASS. It would seem easy for the two
>>>>>>>>>>>>>>>> bits of
>>>>>>>>>>>>>>>> code to get out of sync!
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Second, why do you silently ignore an attempt to redefine an
>>>>>>>>>>>>>>>> anonymous
>>>>>>>>>>>>>>>> class instead of returning JVMTI_ERROR_UNMODIFIABLE_CLASS? The
>>>>>>>>>>>>>>>> restriction on transforming anonymous classes seems no different
>>>>>>>>>>>>>>>> to me
>>>>>>>>>>>>>>>> to the restriction on transforming primitive or array classes.
>>>>>>>>>>>>>>> I believe that there are existing applications, as in the test,
>>>>>>>>>>>>>>> get
>>>>>>>>>>>>>>> all
>>>>>>>>>>>>>>> the loaded classes and try to transform them. These will get
>>>>>>>>>>>>>>> the VM
>>>>>>>>>>>>>>> anonymous class, so we didn't want to give them an error. Or
>>>>>>>>>>>>>>> set CLFH
>>>>>>>>>>>>>>> and vm anonymous classes fall into the load hook. There's
>>>>>>>>>>>>>>> another bug
>>>>>>>>>>>>>>> that Rachel has that ignores them for CFLH (rather than crashing).
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> From the Java standpoint, the existence of vm anonymous classes
>>>>>>>>>>>>>>> are a
>>>>>>>>>>>>>>> implementation detail and not real classes, and it's better to
>>>>>>>>>>>>>>> hide
>>>>>>>>>>>>>>> these as much as possible.
>>>>>>>>>>>>>> I think this is a mistake. While anonymous classes may have
>>>>>>>>>>>>>> started as
>>>>>>>>>>>>>> some obscure VM implementation detail related to JSR-292 and
>>>>>>>>>>>>>> InvokeDynamic they are now entities that are prevalent in a running
>>>>>>>>>>>>>> Java application due to the extensive use of Methodhandles and
>>>>>>>>>>>>>> their
>>>>>>>>>>>>>> use by lambda expressions. Unless we can hide such classes
>>>>>>>>>>>>>> completely
>>>>>>>>>>>>>> (we can't!) we need to define their semantics when treated like
>>>>>>>>>>>>>> other
>>>>>>>>>>>>>> "normal" Java classes. This should have been addressed for JVM
>>>>>>>>>>>>>> TI when
>>>>>>>>>>>>>> anonymous classes came into existence but it wasn't. But we have to
>>>>>>>>>>>>>> deal with it, so simply define them as non-modifiable classes just
>>>>>>>>>>>>>> like array classes and primitives. If code gets an error that is
>>>>>>>>>>>>>> good
>>>>>>>>>>>>>> it _needs_ to get an error because it needs to realize that it is
>>>>>>>>>>>>>> dealing with anonymous classes not "real" ones!
>>>>>>>>>>>>>>
>>>>>>>>>>>>> I disagree, and please read the bug where the consensus is that we
>>>>>>>>>>>>> should ignore these for retransformation. Redefinition is a
>>>>>>>>>>>>> different
>>>>>>>>>>>>> matter because you have to give the class with new bytecodes, which
>>>>>>>>>>>>> would be very bad, and that's why I chose to give an error message.
>>>>>>>>>>>> I don't read such a consensus in the bug report.
>>>>>>>>>>>>
>>>>>>>>>>>>> This is John Rose's answer to a similar question:
>>>>>>>>>>>>>
>>>>>>>>>>>>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-January/038353.html
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>> Yes I added that link to the bug report initially. It reinforces that
>>>>>>>>>>>> retransform/redefinition of VMAC is not intended to work so don't do
>>>>>>>>>>>> that: "Please don't lead your users to rely on them."
>>>>>>>>>>>>
>>>>>>>>>>>> I read more in John's response that the code doing the
>>>>>>>>>>>> transformations
>>>>>>>>>>>> should be skipping the VMAC's, than that the VM code should ignore
>>>>>>>>>>>> the
>>>>>>>>>>>> VMAC's if passed in.
>>>>>>>>>>>>
>>>>>>>>>>>> The current situation is inconsistent and that is what I object to,
>>>>>>>>>>>> most strenuously. When I suggested this be handled through
>>>>>>>>>>>> VM_RedefineClasses::is_modifiable_class I was expecting the VMAC
>>>>>>>>>>>> to be
>>>>>>>>>>>> treated as an unmodifiable class in all cases/sense. It is not
>>>>>>>>>>>> acceptable to me to have IsModifiableClass return false yet
>>>>>>>>>>>> retransform does not report JVMTI_ERROR_UNMODIFIABLE_CLASS. There
>>>>>>>>>>>> should be tests that check that the two are consistent!
>>>>>>>>>>>>
>>>>>>>>>>>> Please, either silently ignore it everywhere, or else deal with it
>>>>>>>>>>>> consistently as unmodifiable.
>>>>>>>>>>>>
>>>>>>>>>>>>> I am not willing to break existing applications.
>>>>>>>>>>>> Any existing application that retransforms an anonymous class is
>>>>>>>>>>>> already in unchartered waters. To quote John "Even if you were
>>>>>>>>>>>> able to
>>>>>>>>>>>> 'transform' one of these classfiles, it wouldn't necessary do what
>>>>>>>>>>>> you
>>>>>>>>>>>> think it should do". So if it is lucky any existing code that
>>>>>>>>>>>> attempts
>>>>>>>>>>>> to transform an anonymous class simply does no harm - but more likely
>>>>>>>>>>>> it gets an error (as per this bug report), or worse it "does
>>>>>>>>>>>> something
>>>>>>>>>>>> you didn't think it would do"! If such code is now run against JDK 9
>>>>>>>>>>>> then I think they would be grateful to be told that they are running
>>>>>>>>>>>> broken code, and exactly where it is broken.
>>>>>>>>>>>>
>>>>>>>>>>>> Cheers,
>>>>>>>>>>>> David
>>>>>>>>>>>>
>>>>>>>>>>>>> Coleen
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Cheers,
>>>>>>>>>>>>>> David
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Coleen
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>> David
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Reran jvmti tests.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>> Coleen
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On 8/10/16 9:32 AM, Coleen Phillimore wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> On 8/9/16 7:40 PM, David Holmes wrote:
>>>>>>>>>>>>>>>>>>> Hi Coleen,
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> On 10/08/2016 4:52 AM, Coleen Phillimore wrote:
>>>>>>>>>>>>>>>>>>>> Summary: Skip VM anonymous classes in retransformation and
>>>>>>>>>>>>>>>>>>>> give an
>>>>>>>>>>>>>>>>>>>> error
>>>>>>>>>>>>>>>>>>>> for redefinition.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Contributed by Tom Rodriguez.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Tested with redefinition colocated tests (tonga) and
>>>>>>>>>>>>>>>>>>>> java/lang/instrument tests, and added test case.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> open webrev at
>>>>>>>>>>>>>>>>>>>> http://cr.openjdk.java.net/~coleenp/8145964.01/webrev
>>>>>>>>>>>>>>>>>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8145964
>>>>>>>>>>>>>>>>>>> Shouldn't anonymous classes be added to the set of
>>>>>>>>>>>>>>>>>>> non-modifiable
>>>>>>>>>>>>>>>>>>> classes - so IsModifiableClass returns false and we just
>>>>>>>>>>>>>>>>>>> add this
>>>>>>>>>>>>>>>>>>> case to VM_RedefineClasses::is_modifiable_class.
>>>>>>>>>>>>>>>>>> Yes, that might be a better way to do it.
>>>>>>>>>>>>>>>>>> thanks,
>>>>>>>>>>>>>>>>>> Coleen
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> ??
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>>>> David
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>>>>>>>> Coleen
More information about the hotspot-dev
mailing list