RFR: 8334513: New test gc/TestAlwaysPreTouchBehavior.java is failing on MacOS aarch64

[Andrew Haley]

On Thu, 22 May 2025 07:41:28 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> I exhumed this old issue that fell through the cracks.
> 
> The test wants to make sure AlwaysPreTouch works by pretouching the java heap and comparing RSS with heap size. 
> 
> This technique is shaky: if the host machine experiences memory pressure, part of the pretouched memory will be swapped out before we measure RSS.
> 
> There is no way to make this bulletproof; still, this test is too useful to abandon it. Therefore I modified this test to make false positives (hopefully) very unlikely. See comment in test for details.
> 
> See old PR: https://github.com/openjdk/jdk/pull/19803

Marked as reviewed by aph (Reviewer).

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

PR Review: https://git.openjdk.org/jdk/pull/25384#pullrequestreview-2866243860