Request for Review (s) - 8060463: ParNew: SurvivorAlignmentInBytes greater then YoungPLABSize cause assert(obj != NULL || plab->words_remaining() < word_sz) failed: Else should have been able to allocate

sangheon sangheon.kim at oracle.com
Thu Mar 24 16:13:12 UTC 2016


Hi Jon,

On 03/24/2016 09:00 AM, Jon Masamitsu wrote:
> Thanks Sangheon, Thomas, and Michail.  Latest versions:
>
> Delta
> http://cr.openjdk.java.net/~jmasa/8060463/webrev_delta.00_01/
Thank you for fixing these.
BTW, could you add a comma in front of 'PLAB size' as well?
And as the test is a new one, I think just '2016' seems correct not 
'2014, 2016'.
I don't need a new webrev for these.

Thanks,
Sangheon


>
> Full
> http://cr.openjdk.java.net/~jmasa/8060463/webrev.01/index.html
>
> Jon
>
>
> On 3/20/2016 8:04 PM, Jon Masamitsu wrote:
>> If SurvivorAlignmentInBytes is larger than the size of the promotion
>> LAB an allocation aligned to SurvivorAlignmentInBytes  may fail. The
>> allocation of the PLAB depends of the size of the object being
>> allocated and if the PLAB is successfully allocated the allocation
>> of the object should succeeded (and is checked by an assertion).
>> For alignments larger than  PLAB, a larger PLAB is sometimes needed
>> to allow for the alignment.
>>
>> The fix does not try to avoid the need for a new PLAB at the
>> next promotion by making the PLAB even larger.  The large
>> values of SurvivorAlignmentInBytes  are allowed but not
>> expected.  I chose not to make the PLAB even larger for a
>> situation I don't expect to see in practice.
>>
>> https://bugs.openjdk.java.net/browse/JDK-8060463
>> http://cr.openjdk.java.net/~jmasa/8060463/webrev.00/
>>
>> Tested with the newly added test which check a range
>> of SurvivorAlignmentInBytes values.
>>
>> Thanks.
>>
>> Jon
>



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