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

[Oli Gillespie]

On Thu, 15 Jun 2023 09:19:12 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`
>  - [ ] Linux x86_64 fastdebug `tier1 tier2 tier3`
>  - [ ] Linux AArch64 fastdebug `tier1 tier2 tier3`

Looks good, thanks :)

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Marked as reviewed by ogillespie (no project role).

PR Review: https://git.openjdk.org/jdk17u-dev/pull/1441#pullrequestreview-1481167362