RFR (urgent, S): 8009836: nsk/regression/b4222717 fails with empty stack trace

[Vladimir Kozlov]

Coleen,

Each allocation in Metaspace (Method is Metadata) is zeroed by calling 
Metablock::initialize() in Metaspace::allocate(). So why these fields 
can have random numbers?

Thanks,
Vladimir

On 3/12/13 11:04 AM, Coleen Phillimore wrote:
>
> Thank you for the code review, Dan.
>
> On 03/12/2013 11:00 AM, Daniel D. Daugherty wrote:
>> On 3/12/13 7:52 AM, Coleen Phillimore wrote:
>>> Summary: zero bit fields missed in Method* and ConstMethod*
>>>
>>> Tested with JPRT and failed test.   The other tests didn't find this
>>> omission.
>>> This bug might be causing JPRT c1 tests to get SEGV with stack
>>> overflows too on the hotspot-rt baseline.
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/8009836/
>>> bug link at http://bugs.sun.com/view_bug.do?bug_id=8009836
>>
>> src/share/vm/oops/constMethod.cpp
>>     No comments.
>>
>> src/share/vm/oops/method.cpp
>>     No comments.
>>
>> Maybe I'm being dense, but I don't see the connection between
>> these code changes and the failure mode we're seeing. Can you
>> explain the connection between these changes and the missing
>> stack traces?
>>
>
> In javaClasses.cpp at line 1560, the method was marked as hidden
> randomly on solaris sparc probably because of the endianness.
>
>      if (method->is_hidden()) {
>        if (skip_hidden)  continue;
>      }
>      bt.push(method, bci, CHECK);
>      total_count++;
>
>> I'm going to guess that the fields that were not explicitly
>> zero were randomly non-zero on some of the Solaris SPARC configs
>> and that caused some confusion.
>
> yes.  I have a feeling that setting flags dont_inline and force_inline
> could also cause confusion but the confusion there was more subtle.
>>
>>
>> How do we know whether all the fields have been properly
>> initialized?
>
> I had some temporary code that checked for the pattern 0xf1 from p =
> this to p< header_size() and manually checked the exceptions. We have a
> lot of gaps in instanceKlass so I couldn't leave the debugging code in.
> So I checked them manually, unfortunately.
>
> thanks,
> Coleen
>>
>>
>> Dan
>>
>>>
>>>
>>> Thanks,
>>> Coleen
>>
>