RFR: 8342041: Test gc/shenandoah/oom/TestClassLoaderLeak.java slow on Windows after JDK-8340490 [v3]

[Aleksey Shipilev]

On Sat, 16 Nov 2024 19:49:20 GMT, Xiaolong Peng <xpeng at openjdk.org> wrote:

>> Fixing the regression on Windows caused by JDK-8340490, the bug is actually caused by different behavior in `os:: os::elapsed_counter()` which I wasn't aware of.  Windows doesn't have nanosecond hi-res clock support, so instead of nanoseconds it returns the the current value of the performance counter([link](https://learn.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancecounter)).
>> 
>> ### Tests
>>  - [x] Verify gc/shenandoah/oom/TestClassLoaderLeak.java on Windows, no regression at all(improved slightly by ~1s comparing to original impl) 
>>  - [x] Run test suites hotspot_gc_shenandoah with linux-aarch64-server-fastdebug
>
> Xiaolong Peng has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Revert all the changes not related to the bug fix
>  - Simplify pace_for_alloc

Ouch. So `elapsed_counter` is nanoseconds only on POSIX! My bad for not catching this during the original review in [JDK-8340490](https://bugs.openjdk.org/browse/JDK-8340490). The fix looks good.

Attn @kdnilsen, @earthling-amzn.

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22172#pullrequestreview-2442489636
PR Comment: https://git.openjdk.org/jdk/pull/22172#issuecomment-2482912074