RFR: 8367473: Shenandoah: Make the detailed evacuation metrics a runtime diagnostic option

[Kelvin Nilsen]

On Fri, 12 Sep 2025 21:29:39 GMT, William Kemper <wkemper at openjdk.org> wrote:

> This chart shows the distribution (as a box plot) of all concurrent evacuation times across all benchmarks and platforms for the past 24 hours (approximately 15K data points in total). Each facet of the chart shows 3 configurations:
> 
> * top: The diagnostic option in this PR is enabled
> * middle: The diagnostic option is disabled
> * bottom: The baseline - this behavior does not exist in the product build.

I'm confused.  It looks like it takes more time when this option is disabled.  And it looks like this branch runs in less time than baseline, when this option is enabled.  Can you explain what I'm missing?

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PR Comment: https://git.openjdk.org/jdk/pull/27238#issuecomment-3289060922