RFR: 8361103: java_lang_Thread::async_get_stack_trace does not properly protect JavaThread [v6]

[Alex Menkov]

On Tue, 5 Aug 2025 05:22:33 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix broken build
>
> src/hotspot/share/classfile/javaClasses.cpp line 1885:
> 
>> 1883: }
>> 1884: 
>> 1885: oop java_lang_Thread::async_get_stack_trace(jobject jthread, TRAPS) {
> 
> Please add a comment describing how the method works for virtual threads, and what returning null implies.

Done.

> src/hotspot/share/classfile/javaClasses.cpp line 1939:
> 
>> 1937:           // Target thread has been unmounted.
>> 1938:           return;
>> 1939:         }
> 
> Shouldn't we set `carrier = true` if we don't return here? Or am I misunderstanding what "carrier" means here?

"carrier" means target is a platform thread with mounted virtual thread.
When `carrier == true` `vframeStream` skips frames of the mounted virtual thread.
Here target is a virtual thread, so we need frames starting from the last frame

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PR Review Comment: https://git.openjdk.org/jdk/pull/26119#discussion_r2255469604
PR Review Comment: https://git.openjdk.org/jdk/pull/26119#discussion_r2255466533