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

[Bengt Rutisson]

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.

> 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.

Thanks for the prompt review!

Bengt
>
> StefanK
>
>>
>> Bengt

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