4-th round RFR (XS) 8068162: jvmtiRedefineClasses.cpp: guarantee(false) failed: OLD and/or OBSOLETE method(s) found

[Coleen Phillimore]

This still looks good to me.
Coleen

On 1/23/15, 9:06 AM, Daniel D. Daugherty wrote:
> Serguei,
>
> Sorry I forgot to close the loop on this review.
>
> I'm OK with the answers below. Thumbs up.
>
> Dan
>
>
> On 1/19/15 10:22 AM, serguei.spitsyn at oracle.com wrote:
>> Coleen,
>>
>> Thank you for answering questions below!
>>
>> Thanks,
>> Serguei
>>
>>
>> On 1/19/15 7:55 AM, Coleen Phillimore wrote:
>>>
>>> On 1/16/15, 9:24 PM, Daniel D. Daugherty wrote:
>>>> > 
>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8068162-JVMTI-old.4/
>>>>
>>>> src/share/vm/memory/universe.hpp
>>>>     No comments.
>>>>
>>>> src/share/vm/memory/universe.cpp
>>>>     No comments.
>>>>
>>>> src/share/vm/prims/jvmtiRedefineClasses.cpp
>>>>     So redefining the Unsafe class is now very expensive because
>>>>     we have to visit the i-table and v-table of every class (and
>>>>     maybe interface?)...
>>>>
>>>>     Based on the bug report 'Unsafe::throw_illegal_access' is some
>>>>     magical method that can appear in any i-table or v-table entry.
>>>>     Maybe only as part of some default methods thing? That's not
>>>>     clear to me so I'm just guessing...
>>>
>>> True.
>>>>
>>>>     Is there some way to limit this visit to classes where the
>>>>     magical method can appear? Or can it really appear anywhere?
>>>
>>> The Unsafe methods can appear in any itable now.   I don't know of a 
>>> way to limit this.  Fortunately, redefining Unsafe seems to be an 
>>> unusual thing to do, except for this stress test.
>>>
>>> Coleen
>>>
>>>>
>>>> Dan
>>>>
>>>>
>>>> On 1/16/15 12:14 PM, serguei.spitsyn at oracle.com wrote:
>>>>> Dan, David H. or David C.,
>>>>>
>>>>> May I ask one of you to look at the webrev below?
>>>>> The issue itself is a little bit tricky, so it is not easy to 
>>>>> review despite the small size.
>>>>>
>>>>> Coleen,
>>>>>
>>>>> Does the webrev matches what we discussed with you?
>>>>> Do you give me a thumbs up?
>>>>>
>>>>> Thanks,
>>>>> Serguei
>>>>>
>>>>> May I ask
>>>>>
>>>>> On 1/13/15 9:47 PM, serguei.spitsyn at oracle.com wrote:
>>>>>> Please, review the fix for:
>>>>>>   https://bugs.openjdk.java.net/browse/JDK-8068162
>>>>>>
>>>>>>
>>>>>> Open webrevs:
>>>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8068162-JVMTI-old.4/ 
>>>>>>
>>>>
>>>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8068162-Test-IsModifiableAgent/ 
>>>>>>
>>>>>>
>>>>>>
>>>>>> Summary:
>>>>>>
>>>>>>    The sun.misc.Unsafe:throwIllegalAccessError() method is used 
>>>>>> in place of a default
>>>>>>    interface method in the itable if a default method was not 
>>>>>> defined in the interface.
>>>>>>    In fact, it happens for two interfaces that purhaps are 
>>>>>> auto-generated:
>>>>>>      java/nio/CharBuffer
>>>>>>      java/nio/HeapCharBuffer
>>>>>>
>>>>>>    This approach creates a problem when the class sun.misc.Unsafe 
>>>>>> is retransformed.
>>>>>>    The Method* pointer to the old (redefined) method in the 
>>>>>> itable triggers an assert
>>>>>>    (see the hs_err log in the bug report).
>>>>>>    Coleen told me that a similar approach is going to be 
>>>>>> implemented for some vtable entries.
>>>>>>    Coleen, thanks for suggesting a better fix for this issue!
>>>>>>
>>>>>>    The fix is to replace the old Unsafe method in the 
>>>>>> itable/vtable with the latest method version.
>>>>>>
>>>>>>
>>>>>> Testing:
>>>>>>   In progress: nsk.jdi.testlist, JTREG java/lang/instrument tests
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Serguei
>>>>>>
>>>>>
>>>>
>>>
>>
>>
>