RFR(xxs): 8202424: Metaspace: on chunk retirement, use correct lower limit on chunksize when adding blocks to free blocks list.
thomas.stuefe at gmail.com
Thu May 3 14:25:04 UTC 2018
On Thu, May 3, 2018 at 3:55 PM, <coleen.phillimore at oracle.com> wrote:
> This looks good - thank you for fixing this!
> On 4/30/18 10:07 AM, Thomas Stüfe wrote:
>> Hi all,
>> please review this small fix, which fixes a small metaspace leak when
>> retiring chunks.
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8202424
>> Some time ago, JDK-8164921 got rid of dark matter by lowering the
>> smallest block size which can be managed by the free block list to
>> When retiring chunks, the leftover space in the old chunk is added to
>> the free block list via SpaceManager::deallocate(). Here, we still
>> unnecessarily assume a lower size limit of TreeChunk<Metablock,
>> FreeList<Metablock> >::min_size(), which is unnecessary high and
>> causes leaks which show up as waste in the retired chunks.
>> By correctly using SmallBlocks::small_block_min_size() when
>> deallocating the leftover chunk space on chunk retirement, we can
>> reduce that kind of waste to almost nil.
>> Thanks, Thomas
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