Review request (S): 7131791 G1: Asserts in nightly testing due to 6976060

[Stefan Karlsson]

On 2012-01-20 17:46, Bengt Rutisson wrote:
>
> Stefan,
>
> Thanks for the prompt review!
>
> Comments inline.
>
> On 2012-01-20 17:21, Stefan Karlsson wrote:
>> On 20 jan 2012, at 17:06, Bengt Rutisson <bengt.rutisson at oracle.com 
>> <mailto:bengt.rutisson at oracle.com>> wrote:
>>
>>>
>>> Hi all,
>>>
>>> Can I have a couple of quick reviews for this small change:
>>> http://cr.openjdk.java.net/~brutisso/7131791/webrev.02 
>>> <http://cr.openjdk.java.net/%7Ebrutisso/7131791/webrev.02>
>>>
>>> This should hopefully fix the 500+ failures in the G1 nightlies. So, 
>>> I would like to get it in before the nightlies tonight.
>>>
>>> The issue is that we call collect() which will trigger a collection 
>>> without protecting the memory that we just allocated for a humongous 
>>> object. The fix (thanks Tony for helping me out!!!) is to fake an 
>>> object and create a handle to it before we call collect.
>>
>> 1067         Handle h((oop)result);  
>> 1068         collect(GCCause::_g1_humongous_allocation);
>> 1069       }
>> 1070       return result;
>> 1071     }
>> Can we really have a handle to uninitialized memory?
>
> The memory is not uninitialized since I fake an object there with the 
> call to CollectedHeap::fill_with_object(result, word_size, false); 
> just before the code you have above.

I missed that.

>
>> Are you sure that the humongous object will not be moved by a full collection. You should probably return h() instead of result.
>
> Humongous objects will not be moved by G1 collections so I think we 
> are ok.

OK. But maybe we should be a bit defensive and return h() here.

StefanK

>
> Thanks for the prompt review!
>
> Bengt
>>
>> StefanK
>>
>>>
>>> Bengt
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/hotspot-gc-dev/attachments/20120120/e0082881/attachment.htm>