RFR: 8169931: 8k class metaspace chunks misallocated from 4k chunk freelist
stefan.karlsson at oracle.com
Tue Nov 22 21:06:09 UTC 2016
On 2016-11-22 18:09, Thomas Stüfe wrote:
> Hi Stefan,
> this change looks good!
> Small nitpick, there exists already a function returning a pointer to
> the free list by chunk index (ChunkManager::free_chunks(index)). You
> could have implemented ChunkManager::list_chunk_size() using this
> function (return free_chunks(index)->size()) and add your assert to
> ChunkManager::free_chunks(index) instead. Or, alternativly, just use
> free_chunks(index)->size() directly instead of adding list_chunk_size().
Sure. I'll send out a new patch including your suggestion.
> Kind Regards, Thomas
> On Tue, Nov 22, 2016 at 3:54 PM, Stefan Karlsson
> <stefan.karlsson at oracle.com <mailto:stefan.karlsson at oracle.com>> wrote:
> Hi all,
> Please, review this patch to fix a bug in ChunkManager::list_index():
> There's a great description of the bug in the bug report:
> There are two conceptual parts of the metaspace. The _class_
> metaspace, and the _non-class_ metaspace. They have different
> chunk sizes, and while querying for the list index of a humongous
> chunk in the class metaspace, the code accidentally matched the
> size against the MediumChunk size of the non-class metaspace.
> I've changed the code to not query against the global ChunkSizes
> enum, but rather the values stored inside the ChunkManager
> instances. Therefore, the list_index() function was changed into
> an instance method.
> I've written a unit test that provoked the bug. It's a simplified
> test with vm asserts instead of gtest asserts. The reason is that
> the ChunkManager class is currently located in metaspace.cpp, and
> is not accessible from the gtest unit tests.
> Testing: jprt, Kitchensink, parallel class loading tests
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