RFR: 8223312: Utilize handshakes instead of is_thread_fully_suspended [v2]

[David Holmes]

On Tue, 20 Oct 2020 10:32:26 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> The main point of this change-set is to make it easier to implement S/R on top of handshakes.
>> Which is a prerequisite for removing _suspend_flag (which duplicates the handshake functionality).
>> But we also remove some complicated S/R methods.
>> 
>> We basically just put in everything in the handshake closure, so the diff just looks much worse than what it is.
>> 
>> TraceSuspendDebugBits have an ifdef, but in both cases it now just returns.
>> But I was unsure if I should remove now or when is_ext_suspend_completed() is removed.
>> 
>> Passes multiple t1-5 runs, locally it passes many jck:vm/nsk_jvmti/nsk_jdi/jdk-jdi runs.
>
> Robbin Ehn has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Removed TraceSuspendDebugBits
>  - Removed unused method is_ext_suspend_completed_with_lock

Still looks good.

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Marked as reviewed by dholmes (Reviewer).

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