RFR: 8320652: ThreadInfo.isInNative needs to be updated to say what executing native code means [v2]

[Bernd]

On Sat, 25 Nov 2023 07:32:20 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Alan Bateman has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - Change link to downcallHandle
>>  - Merge
>>  - Simplify wording
>>  - Merge
>>  - Initial commit
>
> src/java.management/share/classes/java/lang/management/ThreadInfo.java line 552:
> 
>> 550:      * java.lang.invoke.MethodHandle method handle} obtained from the
>> 551:      * {@linkplain java.lang.foreign.Linker native linker}.
>> 552:      *
> 
> This area is new to me, but I happened to be in this code few days back. I'm mostly curious on what the actual definition of a thread being in native means.
> When a thread is executing any of the following,  does it end up being considered as being in a "native method":
> 
> - A syscall (for example, `write()`)
> - A C function exposed by a platform specific library
> - A JNI method (either part of the JDK or the application) which then may or may not do any syscall or C function call on a platform specific library

I would agree, it should state if runtime functions (including those doing a syscall) will be counted here. (For JNi i would not need it to be spelled out, on the other hand it would help, since it makes clear we don’t mean c2 code)

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PR Review Comment: https://git.openjdk.org/jdk/pull/16791#discussion_r1406716462