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

[Coleen Phillmore]

Metachunk::initialize() sets the pattern to 0xf7f7f7f7.
thanks,
Coleen

On 3/12/2013 7:16 PM, Vladimir Kozlov wrote:
> On 3/12/13 3:46 PM, Coleen Phillmore wrote:
>>
>> On 3/12/2013 6:40 PM, Vladimir Kozlov wrote:
>>> 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?
>>
>> With my last checkin, I took out this zero initialization and changed it
>> to 0xf1f1f1f1 in debug mode.
>
> Okay. It would be nice to do the same for Chunks allocatino which do 
> not zero at all.
>
> Vladimir
>
>> Coleen
>>
>>>
>>> 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
>>>>>
>>>>
>>