RFR: 8319244: implement JVMTI handshakes support for virtual threads [v4]

[Serguei Spitsyn]

On Tue, 7 Nov 2023 14:23:34 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   review: get rid of the VM_HandshakeUnmountedVirtualThread
>
> src/hotspot/share/prims/jvmtiEnvBase.cpp line 2416:
> 
>> 2414:   if (!JvmtiEnvBase::is_vthread_alive(_target_h())) {
>> 2415:     return; // JVMTI_ERROR_THREAD_NOT_ALIVE (default)
>> 2416:   }
> 
> Don't we have this check already in JvmtiHandshake::execute()? Same with the other converted functions.

Good suggestion, thanks.
I'm a little bit paranoid about terminated vthreads. :)
Will try to get rid and retest all tiers.

> src/hotspot/share/prims/jvmtiEnvBase.hpp line 490:
> 
>> 488: class JvmtiHandshake : public Handshake {
>> 489:  protected:
>> 490:   static bool is_vthread_handshake_safe(JavaThread* thread, oop vt);
> 
> Not defined, leftover?

Good catch, thanks! Will remove it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16460#discussion_r1386861657
PR Review Comment: https://git.openjdk.org/jdk/pull/16460#discussion_r1386862308