RFR: 8255984: Shenandoah: "adaptive" heuristic is prone to missing load spikes

[Dalibor Topic]

On Fri, 6 Nov 2020 20:00:25 GMT, earthling-amzn <github.com+71722661+earthling-amzn at openjdk.org> wrote:

> This change adds a "reactive" heuristic for triggering concurrent GC cycles.
> 
> The reactive heuristic maintains a margin of error and an allocation spike detection mechanism to trigger cycles somewhat more aggressively than the 'adaptive' heuristic. This heuristic 'reacts' to the outcome of GC cycles by adjusting the sensitivity of the triggers.
> 
> JBS ticket is here: https://bugs.openjdk.java.net/browse/JDK-8255984
> 
> The "adaptive" heuristic remains the default.
> 
> Steps to reproduce and test will follow shortly (there are no new jtreg test failures for Shenandoah with this change).

Hi, 

Please contact me at Dalibor.topic at oracle.com so that I can verify your GitHub account.

Thanks!

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PR: https://git.openjdk.java.net/jdk/pull/1099