RFR: 8227060: Optimize safepoint cleanup subtask order [v3]

[Kim Barrett]

On Sat, 16 Jul 2022 15:22:56 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Most of the analysis in the CR is for code that's removed, but I found one safepoint cleanup task that's unused.  Also the dictionary resizing and symbol/string table rehashing, while rare, could take a long time so I moved them sooner in the list.
>> Tested with tier1-3.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   More Kim improvements.

Looks good.  There may be a couple of followup RFEs to be filed; we can discuss those later.

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Marked as reviewed by kbarrett (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9515