[jdk17u-dev] RFR: 8307348: Parallelize heap walk for ObjectCount(AfterGC) JFR event collection [v2]

[Oli Gillespie]

On Wed, 5 Jul 2023 09:17:14 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Improves ObjectCount JFR events that take considerable time at GC pause. While the event is still heavy, the parallelization helps to avoid unnecessarily large stalls. 
>> 
>> The backport is not clean, because there are number of contextual differences: `WorkGang`, `WithUpdatedActiveWorkers` and other renames did not happen yet. I had to massage the patch to fit 17u better.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 fastdebug `jdk/jfr serviceability/sa`
>>  - [x] Linux x86_64 fastdebug `tier1 tier2 tier3`
>>  - [x] Linux AArch64 fastdebug `tier1 tier2 tier3`
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:
> 
>   Backport 540c706bbcbb809ae1304aac4f2a16a5e83cb458

Marked as reviewed by ogillespie (no project role).

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PR Review: https://git.openjdk.org/jdk17u-dev/pull/1441#pullrequestreview-1514076348