RFR: 8223312: Utilize handshakes instead of is_thread_fully_suspended [v3]

[Richard Reingruber]

On Wed, 21 Oct 2020 16:45:53 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:
>> 
>>  - Fixed merge miss
>>  - Merge branch 'master' into 8223312-Utilize-handshakes-instead-of-is_thread_fully_suspended
>>  - Merge fix from Richard
>>  - Merge branch 'master' into 8223312-Utilize-handshakes-instead-of-is_thread_fully_suspended
>>  - Removed TraceSuspendDebugBits
>>  - Removed unused method is_ext_suspend_completed_with_lock
>>  - Utilize handshakes instead of is_thread_fully_suspended
>
> src/hotspot/share/prims/jvmtiEnv.cpp line 1646:
> 
>> 1644: // java_thread - pre-checked
>> 1645: jvmtiError
>> 1646: JvmtiEnv::PopFrame(JavaThread* java_thread) {
> 
> So I'm a bit confused why I'm seeing PopFrame() changes here that are
> related to @reinrich's EscapeBarrier work. I've seen mention of picking
> up a patch during this review from @reinrich so may that's why. I don't
> see anything wrong with the changes, but I am confused why they are
> here in this review.

This change moves code with EscapeBarriers (integrated with #119) into a handshake. That does not work because object reallocation can safepoint. So the EBs are pulled out of the handshake.

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PR: https://git.openjdk.java.net/jdk/pull/729