RFR: 8335167: Test runtime/Thread/TestAlwaysPreTouchStacks.java failed with Expected a higher ratio between stack committed and reserved [v2]

[David Holmes]

On Mon, 2 Sep 2024 07:53:01 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> The test program runs once with PreTouch and another without PreTouch stacks. For each run the amounts of reserved and committed stack regions are held and then compared the ratio of with and without PreTouch. The ratio of PreTouch test should be greater than the other (because there will be higher committed regions due to pre-touching the pages).
>> 
>> The specific test is run on linux-x64, windows-x64 and macosx-aarch64 in tiers1-5.
>
> Afshin Zafari has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'origin/master' into _8335167_higher_ratio_commit
>  - 8335167: Test runtime/Thread/TestAlwaysPreTouchStacks.java failed with Expected a higher ratio between stack committed and reserved
>  - 8335167: Test runtime/Thread/TestAlwaysPreTouchStacks.java failed with Expected a higher ratio between stack committed and reserved

I can't discern what the core changes are here such that the now passes more reliably. Why did you change from distinct @test cases to running the test in each mode within a single @test? The refactoring makes it very difficult to see what has actually changed and you haven't described it.

Also what testing did you do for this? What was the old failure rate?

Thanks

test/hotspot/jtreg/runtime/Thread/TestAlwaysPreTouchStacks.java line 99:

> 97:       ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder(vmArgs);
> 98:       OutputAnalyzer output = new OutputAnalyzer(pb.start());
> 99:       output.reportDiagnosticSummary();

Pre-existing, but this should go at the end, otherwise if a test fails you will get two summaries printed.

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PR Review: https://git.openjdk.org/jdk/pull/20531#pullrequestreview-2289066514
PR Review Comment: https://git.openjdk.org/jdk/pull/20531#discussion_r1749731338