RFR (S): 8025228: assert(new_entry->reserved_words() == vs_word_size) fails in nightly

Bengt Rutisson bengt.rutisson at oracle.com
Tue Sep 24 06:49:20 PDT 2013


Hi Thomas,

Good point about the test name. Here is an updated webrev:

http://cr.openjdk.java.net/~brutisso/8025228/webrev.01/

Thanks,
Bengt

On 9/24/13 2:02 PM, Thomas Schatzl wrote:
> Hi,
>
> On Tue, 2013-09-24 at 13:32 +0200, Bengt Rutisson wrote:
>> Hi everyone,
>>
>> Could I have a couple of reviews for this change?
>>
>> http://cr.openjdk.java.net/~brutisso/8025228/webrev.00/
>>
>> https://bugs.openjdk.java.net/browse/JDK-8025228
>>
>> We hit this assert in VirtualSpaceList::get_new_chunk() when we have
>> an allocation that is larger than VirtualSpaceSize and that is not
>> aligned with vm_allocation_granularity. The reason is that the
>> VirtualSpace will grow with sizes aligned to vm_allocation_granularity
>> but we we only guarantee that the sizes we want to grow with are page
>> aligned. This means that we only hit this assert on platforms
>> (Windows) where vm_allocation_granularity > vm_page_size.
>>
>> Since VirtualSpaceSize is vm_allocation_granularity aligned on all
>> platforms we only hit the assert for allocations larger than that size
>> due to this line:
>>
>> 1224           size_t grow_vs_words =
>> 1225             MAX2((size_t)VirtualSpaceSize,
>> aligned_expand_vs_by_words);
>>
>> The fix is to make sure that the grow_vs_words value is
>> vm_allocation_granularity aligned and not just page size aligned.
> The change looks fine by me, but I am no expert in that area.
>> Testing:
>>
>> Added a unit test that fails this way on Windows before my fix:
>>
>> Running internal VM tests
>> Running test: TestReservedSpace_test()
>> Running test: TestReserveMemorySpecial_test()
>> Running test: TestVirtualSpace_test()
>> Running test: MetaspaceAux_test()
> Because it is somewhat fitting to this particular issue, could you
> rename "MetaspaceAux_test" to "TestMetaspaceAux_test" similar to the
> others?
>
> Thanks,
>    Thomas
>
>



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