[9] RFR (XS): 8151623: Zap freed Metaspace chunks in non-product binaries

[Vladimir Ivanov]

Stefan, Jon, thanks for the reviews!

Last question: what do you think about moving the constant declaration 
to globalDefinitions.hpp?

http://cr.openjdk.java.net/~vlivanov/8151623/webrev.04

Best regards,
Vladimir Ivanov


On 3/15/16 11:51 AM, Stefan Karlsson wrote:
> Hi Vladimir,
>
> On 14/03/16 19:48, Vladimir Ivanov wrote:
>> Jon,
>>
>> Updated version:
>> http://cr.openjdk.java.net/~vlivanov/8151623/webrev.03/
>
> There's a type mismatch here:
>
> 149 static const size_t metadata_chunk_initialize = 0xf7f7f7f7;
> 150
> 151 void mangle(juint word_value = metadata_chunk_initialize); Otherwise, this looks good.
>
> Thanks,
> StefanK
>
>>
>>> If there is a mistake in the mangling of a Metablock, that would
>>> show up when the Metaspace shrinks.  Can you check that the testing
>>> has some Metaspace shrinking.  I think that -Xlog:gc*=trace would
>>> show the needed output.
>> Thanks for the hint! It found one problem with -Xlog:gc*=trace itself:
>> BlockFreelist keeps the tree of free blocks inside Metachunks and
>> dumps the content from the destructor.
>>
>> Mangling breaks it because it happens earlier and destroys the free
>> list structure by the time BlockFreelist destructor is called.
>>
>> I fixed it by dumping the free list content before Metachunks are
>> mangled.
>>
>> I ran a stress test on class loading and ensured there's no memory
>> leak in Metaspace.
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> PS: maybe add a -Xlog:gc,metaspace,freelist=trace event for metachunk
>> mangling?
>