RFR: 8258284: clean up issues with nested ThreadsListHandles [v2]

[Robbin Ehn]

On Fri, 18 Dec 2020 18:09:12 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> While working on JDK-8231627, I discovered there were issues with nested
>> ThreadsListHandles. I added a new test to verify how ThreadsListHandles and
>> nested ThreadsListHandles are supposed to work. I found two bugs:
>> 
>> 1) A failure to restore the expected _threads_hazard_ptr when a nested
>>     ThreadsListHandle is destroyed.
>> 
>> 2) A failure to decrement _nested_threads_hazard_ptr_cnt when a nested
>>     ThreadsListHandle is destroyed.
>> 
>> The second failure mode is what tripped up my fix for JDK-8231627 so that
>> bug fix depends on this bug fix.
>> 
>> Mach5 Tier[1-3] testing has no regressions (macOSX testing is incomplete at the moment).
>
> Daniel D. Daugherty has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Resolve @fisk CR about using Atomic::store().

Thanks

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Marked as reviewed by rehn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1844