RFR: 8338383: Implement JEP 491: Synchronize Virtual Threads without Pinning [v12]

[Patricio Chilano Mateo]

On Mon, 28 Oct 2024 23:59:55 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> So it sounds like the adjustment at line 119 is a bug fix, but what I don't understand is why we weren't seeing problems before.  Something in this PR exposed the need for this change.
>
>> What are we counting now with MaskFillerForNativeFrame that we weren't counting before this change? in MaskFillerForNative::set_one.
>>
> The number of oops in the parameter's for this native method. For Object.wait() we have only one, the j.l.Thread reference. But for synchronized native methods there could be more.

> So it sounds like the adjustment at line 119 is a bug fix, but what I don't understand is why we weren't seeing problems before. Something in this PR exposed the need for this change.
>
Because before this PR we never freezed interpreter frames belonging to native methods.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21565#discussion_r1819909304