how to find out the types of the surviving objects after a GC

[Tony Guan]

Hi John,

got it!

Klass::cast(klass())->external_name()  should be the answer.

Thanks!

Tony (Xiaohua Guan)



On Fri, Nov 5, 2010 at 5:45 PM, Tony Guan <guanxiaohua at gmail.com> wrote:
> Hi John,
>
> Thanks!
>
> I understand that the klassOop  maybe compressed, so I need to call
> klass() for the proper access. But I am still wandering in the
> klassOop definition, having no clue for getting the name of the java
> class. While I think eventually I will get there, any hint is welcome
> at any time!
>
> Thanks again!
>
> Tony (Xiaohua Guan)
>
>
>
> On Fri, Nov 5, 2010 at 5:25 PM, John Cuthbertson
> <john.cuthbertson at oracle.com> wrote:
>> Hi Tony,
>>
>> The second word in each oop is the klassOop (a pointer to the structure
>> describing the class/type). From that you can get the class name etc. For
>> arrays the third word is the array length.
>>
>> Regards,
>>
>> JohnC
>>
>> On 11/05/10 12:11, Tony Guan wrote:
>>>
>>> Dear all,
>>>
>>> We are now interested in the types of the surviving objects after a
>>> GC.  Currently, I plan to do like this:
>>>
>>> 1. record the top() address of the old generation before a minor GC.
>>> 2. iterate oops in the increased portion(between the old top and the
>>> new top) of the old generation
>>> 3. for each oop, find out what's the type of the object it stands for.
>>>
>>> As I am studying the existing code from hotspot, I also realize that
>>> this maybe a simple question for you:
>>> Is there an easy way tell the types from the oop? Or will there be a
>>> problem in my current plan?
>>>
>>> Thanks as always!
>>>
>>> Tony (Xiaohua Guan)
>>>
>>
>>
>