RFR: 8186706: ArchivedObjectCache obj_hash() is broken

[Jiangli Zhou]

Hi Ioi,

The table was not changed to be allocated as ResourceObj::C_HEAP. I see ‘ALLOC_TYPE’ only applies to the Nodes in the ResourceHashtable.

Thanks,
Jiangli

> On Aug 23, 2017, at 6:03 PM, Ioi Lam <ioi.lam at oracle.com> wrote:
> 
> Hi Jiangli,
> 
> Since the table is allocated as ResourceObj::C_HEAP, it's better to delete it afterwards to avoid memory leaks
> 
>   {
>     NoSafepointVerifier nsv;
> 
>     // Cache for recording where the archived objects are copied to
>     MetaspaceShared::create_archive_object_cache();
> 
>     tty->print_cr("Dumping String objects to closed archive heap region ...");
>     NOT_PRODUCT(StringTable::verify());
>     // The string space has maximum two regions. See FileMapInfo::write_archive_heap_regions() for details.
>     _string_regions = new GrowableArray<MemRegion>(2);
>     StringTable::write_to_archive(_string_regions);
> 
>     tty->print_cr("Dumping objects to open archive heap region ...");
>     _open_archive_heap_regions = new GrowableArray<MemRegion>(2);
> MetaspaceShared::dump_open_archive_heap_objects(_open_archive_heap_regions);
> 
> +   MetaspaceShared::create_archive_object_cache();
> 
>   }
> 
> + static void delete_archive_object_cache() {
> +   CDS_JAVA_HEAP_ONLY(delete _archive_object_cache; _archive_object_cache = NULL;);
> + }
> 
> Thanks
> - Ioi
> 
> On 8/23/17 4:24 PM, Jiangli Zhou wrote:
>> Please review the following webrev that fixes the ArchivedObjectCache obj_hash() issue. The patch was from Ioi (thanks!). I will count myself as a reviewer.
>> 
>> bug: https://bugs.openjdk.java.net/browse/JDK-8186706?filter=14921
>> webrev: http://cr.openjdk.java.net/~jiangli/8186706/webrev.00/
>> 
>> ArchivedObjectCache obj_hash() computes hash using incorrect address. The fix is to use the correct oop address. The default ResourceHashtable size is 256, which is too small when large number of objects are archived. The table is now changed to use a much larger (15889) size. The ArchivedObjectCache issue was noticed when one test times out on slower linux arm64 machine. With the fix the test finishes without timeout.
>> 
>> Tested with tier4-comp tests.
>> 
>> Thanks,
>> Jiangli
>