RFR 8003421: NPG: Move oops out of InstanceKlass into mirror

[Coleen Phillimore]

Thanks Stefan, Staffan, Dean, and David for comments.   I have a new 
webrev and have tested this new change that doesn't break hprof format 
in the SA and fixed things from the code reviews.  I didn't move 
component mirror.  I have to think about this more.   Please re-review.

http://cr.openjdk.java.net/~coleenp/8003421_2/

Thanks,
Coleen


On 05/21/2013 11:01 AM, Coleen Phillimore wrote:
>
> On 05/21/2013 09:18 AM, Staffan Larsen wrote:
>>>>> Net footprint change is zero except that these fields are in Java 
>>>>> heap
>>>>> rather than metaspace.  This helps a little with InstanceKlass size
>>>>> which is in fixed size space with UseCompressedKlassPointers. 
>>>>> Included
>>>>> serviceability because there were SA changes to code that I don't 
>>>>> know
>>>>> is used.
>>>> Unsure about the SA changes. Basically you just removed access to 
>>>> the pd and signers, rather than changing it to allow access via the 
>>>> new path. That said I don't know SA so don't know whether it makes 
>>>> sense for SA to access things that are logically part of 
>>>> java.lang.Class; or whether it can access them more directly anyway 
>>>> because they are logically part of java.lang.Class.
>>>>
>>> I did remove these from instanceKlass.  It doesn't appear in the SA 
>>> that it digs into the java mirror so there was nowhere to put these 
>>> fields.   The code that I took out was in places that may not be 
>>> used and may be bit rotted.   I added serviceability team to the 
>>> review request so someone could comment.  I already asked Staffan 
>>> about this.
>> Reading this in more detail, I'm a little worried about the change in 
>> hprof output. The change in HeapHprofBinWriter actually breaks the 
>> hprof binary format, leading to unparseable files. Granted, this is 
>> hprof output when invoked either in SA or with "jmap -F" so it won't 
>> be used by very many people and I can't find any tests that do this.
>>
>> I think we need to find a way to add this information back.
>
> Hi,  I didn't want to break the hprof format so I added it back to 
> return null for protection domain and signers.  There doesn't seem to 
> be a way in SA to read from the mirror but I posted suggested code 
> once this sort of thing is implemented.   See:
>
> http://cr.openjdk.java.net/~coleenp/8003421_2/agent/src/share/classes/sun/jvm/hotspot/utilities/HeapGXLWriter.java.udiff.html 
>
> http://cr.openjdk.java.net/~coleenp/8003421_2/agent/src/share/classes/sun/jvm/hotspot/utilities/HeapHprofBinWriter.java.udiff.html 
>
>
> I can file a bug against the SA to get the correct information or 
> decide whether this is something you need to support in this manner.
>
> thanks,
> Coleen
>
>>
>> /Staffan
>