RFR: 8229012: When single stepping, the debug agent can cause the thread to remain in interpreter mode after single stepping completes [v4]

[Chris Plummer]

On Mon, 17 Feb 2025 09:14:12 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> Chris Plummer has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix white space errors.
>
> src/jdk.jdwp.agent/share/native/libjdwp/stepControl.c line 899:
> 
>> 897:     }
>> 898: 
>> 899:     if (step->pending) {
> 
> Is this condition the same as new line 876 above?  (I don't see where the intervening calls would affect it?)

That's a good question. I hadn't noticed the extra check for step->pending, and it looks like that was also in place for the previous version that relied on calling ClearFramePop on each outstanding NotifyFramePop. I think it is just bit rot as the code initially evolved. If it was possibly for the flag to be cleared by some other thread (I actually think it might be, but need to look closer), this extra check is not of much help since it could be cleared after the check. Let me look into this a bit more.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23182#discussion_r1958993698