RFR: 8299414: JVMTI FollowReferences should support references from VirtualThread stack [v2]

[Alex Menkov]

On Wed, 5 Apr 2023 20:25:39 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   aree -> are
>
> test/hotspot/jtreg/serviceability/jvmti/vthread/FollowReferences/VThreadStackRefTest.java line 43:
> 
>> 41:  * mounted and unmounted virtual threads and reports correct thread id
>> 42:  * (for mounted vthread it should be vthread id, and not carrier thread id).
>> 43:  * Additionally tests that references from platform threads aree reported correctly
> 
> "aree" -> "are"

Fixed

> test/hotspot/jtreg/serviceability/jvmti/vthread/FollowReferences/VThreadStackRefTest.java line 93:
> 
>> 91:             createObjAndWait(VThreadMountedJNIReferenced.class);
>> 92:             Reference.reachabilityFence(referenced);
>> 93:         });
> 
> This code used to use a java loop to keep busy, but now it relies on a sleep loop in native code. Was the java loop problematic?

No. I had a failure of the test due racing, but I believe the reason was lack of synchronization.
I decided to simplify the test - 2 virtual threads are enough and as the test verifies "JNI local on top frame" case, it needs block in native call anyway, so I use it to prevent unmount too.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13254#discussion_r1159022346
PR Review Comment: https://git.openjdk.org/jdk/pull/13254#discussion_r1159020544