RFR: 8264008: Incorrect metaspace statistics after JEP 387 when UseCompressedClassPointers is off [v2]

[Jie Fu]

On Tue, 23 Mar 2021 06:35:24 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> Yes, this makes sense. Thanks for fixing this.
> 
> The problem is that `is_class_space_allocation` is ambiguous. The way it is implemented it answers the question "should this be allocated from class space". But in this statistics, it is used as a simple "is this a class space type".
> 
> What concerns me is that we did not find this earlier. Can you please add a test run for at least one of the failing tests to also execute with compressed oops off?
> 
> Even better would be an own regression test, e.g. as part of the gtests. Can be very simple, if UseCompressedClassPointers is off, MetaspaceUtils::committed_words should return 0 for class type. Then we can add another gtest run to the gtest runner jtreg tests with that option (possibly in a separate RFE).

Thanks @tstuefe for your review.

A test run has been added in jdk/jfr/event/gc/heapsummary/TestHeapSummaryEventDefNewSerial.java.
Will add more specific tests in a separate RFE.
Thanks.

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PR: https://git.openjdk.java.net/jdk/pull/3142