RFR: 8305995: Use full dominant search for regions [v2]

[Kirill A. Korinsky]

On Fri, 14 Apr 2023 18:29:58 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Kirill A. Korinsky has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
>> 
>>   8305995: Use full dominant search for regions
>>   
>>   This is a fix for the regression introduced by
>>   da43cb5e463069cf4dafb262664f0d3d7c2e0eac in fix 8224957.
>>   
>>   This regression was found while attempting to migrate an application
>>   from JDK 1.8 to JDK 17, by running internal benchmarks, and while
>>   investigating abnormal memory usage for about 4 times more from one of
>>   them.
>>   
>>   The regression appears in provided JMH benchmark, which builds a RB-tree
>>   based map which contains 780 entries with primitive integers.
>>   
>>   This benchmark was run with `ParallelGC` on different JVMs: `JDK
>>   1.8.0_362`, `JDK 11.0.18`, `JDK 13.0.13`, `JDK 15.0.9`, `JDK 17.0.6`,
>>   `JDK 19.0.2` and `JDK 20`. This allows to see that something has changed
>>   between 13 and 15, and that the memory footprint for this code has
>>   increased from nothing `≈ 10⁻³ ` to `7536` bytes per operation.
>>   
>>   Proposed fix reduces the memory footprint expected value.
>
> And add benchmark's output as comment and what machine you used to run it.

@vnkozlov may you suggest any meaningful name? :) `RBTreeSearch` is good enough?

-------------

PR Comment: https://git.openjdk.org/jdk/pull/13453#issuecomment-1509076244