RFR: 8261448: Preserve GC stack watermark across safepoints in StackWalk [v2]

[Stefan Karlsson]

On Fri, 12 Feb 2021 23:14:47 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Make KeepStackGCProcessedMark reentrant; Place a KeepStackGCProcessedMark in StackWalker::fetchFirstBatch()
>
> Nesting code looks wrong.

I incorrectly read Erik's comment as "Nesting code looks **good**", so I created a unit test to show the problem with the patch:
https://github.com/stefank/jdk/commit/8760f1b0409b3cccf76a8ea417b90e66da31af72

Maybe you could build a few more test based on this?

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PR: https://git.openjdk.java.net/jdk/pull/2500