RFR: 8338526: Don't store abstract and interface Klasses in class metaspace

[Roman Kennke]

On Tue, 3 Sep 2024 15:50:13 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>>> > I don't think the costs for two address comparisons matter, not with the comparatively few deallocations that happen (few hundreds or few thousand). If deallocate is hot, we are using metaspace wrong.
>>> 
>>> MethodData does a lot of deallocations from metaspace because it's allocated racily. It might be using Metaspace wrong.
>> 
>> I think that should be okay. This should still be an exception. I have never seen that many deallocations happening in customer cases.
>
>> @tstuefe Do you have more comments on this PR?
> 
> Sorry, I was swamped the past days. I'll take a look tomorrow.

AFAIK, @tstuefe (currently on vacation) has a working prototype of a Klass-lookup-table with good performance and reasonable ‘management cost’. This would make make many things much simpler and also help solve this problem because it makes irrelevant where a Klass lives.

Roman

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PR Comment: https://git.openjdk.org/jdk/pull/19157#issuecomment-2401435370