RFR: 8293218: serviceability/tmtools/jstat/GcNewTest.java fails with "Error in the percent calculation" [v3]

[Kevin Walls]

On Fri, 9 Sep 2022 09:28:38 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> Test update to cope with heap size changing (shrinking) in the early life of the test app.
>> 
>> A change in GC timing affects this test which reads eden size and heap size.  Both eden and heap are likely to shrink initially for this test.  Failures were that heap size shrank after reading eden size, such that eden appeared to be >100% of heap.
>> Recognising a shrinking heap and retrying resolves this.  
>> 
>> (Re-ordering to read heap size then eden would be enough to make the check in provokeGc work.  But it would allocate sometimes a very small fraction of the heap, which is not the intent.)
>
> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Clarify that loop is for checking heap not changing.  Exception if continually changing.

OK, yes that technique in GcProvokerImpl comes in with:

date:        Thu Jan 14 15:35:21 2016 +0300
summary:     8130063: Refactoring tmtools jstat and jstack tests to jtreg

..but IIRC tmtools is a testsuite being integrated into the JDK source, so the code is much older.  Does this change anything? 8-)

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PR: https://git.openjdk.org/jdk/pull/10218