8u60 backport RFR (M) 8067662: "java.lang.NullPointerException: Method name is null" from StackTraceElement.<init>

[Coleen Phillimore]

This backport looks good.  Why didn't the patch apply cleanly?  It seems 
mostly the same to me.
Thanks,
Coleen

On 4/6/15, 7:50 PM, serguei.spitsyn at oracle.com wrote:
> Coleen and Dan,
>
> I'm asking you as the jdk  9 reviewers...
>
> Please, let me know if you have any chance and plans to review this.
> Would it be enough to have just one (R) reviewer for a non-clean 
> backport?
>
> Thanks,
> Serguei
>
>
>
> On 4/2/15 5:03 PM, serguei.spitsyn at oracle.com wrote:
>> Please, review the jdk 8u60 backport for:
>>   https://bugs.openjdk.java.net/browse/JDK-8067662
>>
>> 8u60 hotspot webrev:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8067662-JVMTI-trace.8u60 
>>
>>
>> 8u60 webrev for unit test update (the fix applies cleanly):
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8067662-JVMTI-trace-test.8u60 
>>
>>
>>
>>
>> 9 hotspot webrev:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8067662-JVMTI-trace.2 
>>
>>
>> 9 webrev for unit test update:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8067662-JVMTI-trace-test.2 
>>
>>
>>
>> Summary:
>>   The 9 fix can not be applied cleanly so that I have to rework the 
>> fix a little bit.
>>
>>   An NPE is trown in a thread dumping via JMX when doing CPU 
>> profiling in NetBeans Profiler and VisualVM.
>>   The issue is that the methods and related klass versions are not 
>> kept alive if a class redefinition
>>   takes place between catching a Throwable and taking a thread dump.
>>   It can result in loosing an obsolete method, and so, the 
>> reconstruction of method name becomes impossible.
>>   In such a case, the null reference is returned instead of a valid 
>> method name.
>>
>>   The solution is to use current klass version and method orig_idnum 
>> instead of ordinary method idnum
>>   to find required method pointer. In the worst case when the related 
>> klass version is gone
>>   (was not included to or was removed from the previous_versions 
>> linked list), a saved method name
>>   CP index of the latest klass version can be used to restore the 
>> method name.
>>   The footprint extra overhead for this approach is u2 per stack frame.
>>
>> Testing in progress:
>>   In progress: nsk redefine classes tests, JTREG java/lang/instrument
>>
>>
>> Thanks,
>> Serguei
>>
>