RFR(S) 8244536 cds/DeterministicDump.java failed: File content different

[Yumin Qi]

Thanks. It looks OK to me then.

Thanks
Yumin

On 5/13/20 10:52 AM, Ioi Lam wrote:
>
>
> On 5/13/20 10:42 AM, Yumin Qi wrote:
>> HI, Ioi
>>
>>   I have a question here:
>>
>>    _version = CURRENT_CDS_ARCHIVE_VERSION;
>>    _alignment = alignment;
>>    _obj_alignment = ObjectAlignmentInBytes;
>>    _compact_strings = CompactStrings;
>> + if (HeapShared::is_heap_object_archiving_allowed()) {
>>    _narrow_oop_mode = CompressedOops::mode();
>>    _narrow_oop_base = CompressedOops::base();
>>    _narrow_oop_shift = CompressedOops::shift();
>> + _heap_end = CompressedOops::end();
>> + }
>>    _compressed_oops = UseCompressedOops;
>>    _compressed_class_ptrs = UseCompressedClassPointers;
>>    _max_heap_size = MaxHeapSize;
>>    _narrow_klass_shift = CompressedKlassPointers::shift();
>> - if (HeapShared::is_heap_object_archiving_allowed()) {
>> - _heap_end = CompressedOops::end();
>> - }
>>
>> _heap_end seems not calculated if heap object not archived.
>>
>
> Hi Yumin,
>
> Thanks for your comment.
>
> The header is cleared to zeros in here:
>
> FileMapInfo::FileMapInfo(bool is_static) {
>   ...
>   _header = (FileMapHeader*)os::malloc(header_size, mtInternal);
>   memset((void*)_header, 0, header_size);
>
> So if heap objects are not archived, _narrow_oop_mode, 
> _narrow_oop_base, _narrow_oop_shift and _heap_end will all be zeros. 
> These fields will not be used during runtime.
>
> Thanks
> - Ioi
>
>
>>
>>
>> Thanks
>> Yumin
>>
>> On 5/11/20 2:00 PM, Ioi Lam wrote:
>>> https://bugs.openjdk.java.net/browse/JDK-8244536
>>> http://cr.openjdk.java.net/~iklam/jdk15/8244536-DeterministicDump-fails-on-windows.v01/ 
>>>
>>>
>>> I fixed 2 issues that are likely to happen on Windows due to
>>> it aggressive ASLR policy (address space layout randomization).
>>> These would cause the CDS archive to have non-deterministic
>>> contents:
>>>
>>> [1] Don't save the _narrow_oop_{mode,shift,base} header fields
>>>     for platforms (including Windows) that don't support heap
>>>     archiving, as these fields would be useless anyway.
>>>
>>>     This was the cause of the failure cases in the bug report.
>>>
>>> [2] Fixed a hashtable that would lay out differently if
>>>     the archive was relocated during -Xshare:dump. This is also
>>>     likely to happen on Windows but is not as frequent as #1.
>>>
>>>     Added test case for [2] in DeterministicDump.java (using
>>>     -XX:ArchiveRelocationMode=1).
>>>
>>>
>>> Test on mach5 with tiers 1/2/3.
>>>
>>> Thanks
>>> - Ioi
>>
>