RFR: 8261495: Shenandoah: reconsider update references memory ordering [v4]

[Aleksey Shipilev]

On Fri, 19 Mar 2021 11:39:11 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:
>> 
>>  - Comment touchup
>>  - Specialize out witness-checking methods, drop acquire again
>>  - Even more explanation
>>  - Move the comment
>>  - Also handle clearing the oops
>>  - Minor touchups to the comment
>>  - Merge branch 'master' into JDK-8261495-shenandoah-updaterefs-memord
>>  - Use release only
>>  - Do acq_rel instead
>>  - 8261495: Shenandoah: reconsider update references memory ordering
>
> Looks good to me.

@rkennke, @zhengyu123 -- please take a look again. Now that JDK-8261579 is there, the performance data is available (PR body), and it seems to be ready to go.

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PR: https://git.openjdk.java.net/jdk/pull/2498