RFR: 8268829: Provide an optimized way to walk the stack with Class object only [v8]

[Alan Bateman]

On Wed, 30 Aug 2023 15:03:27 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Mandy Chung has updated the pull request incrementally with three additional commits since the last revision:
>> 
>>  - update mode to be int rather than long
>>  - update tests
>>  - Review feedback on javadoc
>
> src/java.base/share/classes/java/lang/StackStreamFactory.java line 694:
> 
>> 692:             // no method information is available; should just filter
>> 693:             // "Continuation::yield0".
>> 694:             return classFrames[index].declaringClass() == Continuation.class;
> 
> Is that going to be an issue if by chance the frame is some other method on continuation?
> Could that comment be clarified a bit?
> I am not sure what is meant by `should just filter "Continuation::yield0"`; Does it mean: that's what we should do, but we can't, so we filter any method on `Continuation` instead? Or does it mean: the only method we expect here if declaringClass is `Continuation` is `yield0`, so the line below should only filter out `Continuation::yield0`?

The Continuation frames around enter and yielding are hidden. Continuation.yield0 was the only frame that required special handling here, it may need to be re-checked to see if it is still required when using SHOW_HIDDEN_FRAMES.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15370#discussion_r1310462843