RFR: 8293218: serviceability/tmtools/jstat/GcNewTest.java fails with "Error in the percent calculation" [v4]

[Daniel D. Daugherty]

On Fri, 16 Sep 2022 16:59:10 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:
> 
>   Remove else. Add comment.

I'm good with the changes. Thanks for adding the retry when we
observe the heap shrinking.

It's not clear what kind of testing has already been done:

- JDK-8293218 failures have been seen in Tier[78].
- JDK-8293564 failures have been seen in Tier7.
- Both tests also run in Tier[13].

I recommend doing Tier1 testing and then use that build-ID for
Tier3 and Tier7 testing. The tests also run in Tier[456] testing,
but I think you can skip those.

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Marked as reviewed by dcubed (Reviewer).

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