RFR(s): 8169870: CDS: "assert(partition_size <= size()) failed: partition failed" on 32 bit JVM

[Jiangli Zhou]

Hi Chris,

> On Nov 19, 2016, at 11:24 AM, Chris Plummer <chris.plummer at oracle.com> wrote:
> 
> Hi Jiangli,
> 
> The changes look fine.

Thanks for the review!

> 
> BTW, we also have LimitSharedSizes.java. Seems there is some overlap with this test. I'm not sure how we ended up with both. Also not sure how LargeSharedSpace.java caught this problem and LimitSharedSizes.java. I guess it was just unlucky with the size it chose.

The ones used by the new LargeSharedSpace.java are extremely large sizes (=> 1G). LimitSharedSizes.java mainly focuses on testing very small space sizes, and makes sure if the space size is too small the VM should not crash.

Thanks,
Jiangli


> 
> Chris
> 
> On 11/18/16 6:14 PM, Jiangli Zhou wrote:
>> Please review following fix for JDK-8169870 <https://bugs.openjdk.java.net/browse/JDK-8169870>.
>> 
>>   http://cr.openjdk.java.net/~jiangli/8169870/webrev.00/ <http://cr.openjdk.java.net/~jiangli/8169870/webrev.00/>
>> 
>> This is an old bug but only discovered recently. Thanks Dmitry for reporting the issue. During CDS dump time, the VM tries to allocate memory (by calling ReservedSpace()) for shared space at the top of the java heap. If ReservedSpace() fails, it tries to allocate the memory at a different location by calling ReservedSpace() again. After the second ReservedSpace() call, it initializes the shared space without checking if the second allocation attempt is successful or not.
>> 
>> Added a new case in LargeSharedSpace.java and tested on both 32-bit and 64-bit platforms.
>> 
>> Thanks,
>> Jiangli
> 
>