RFR: 8296125: Add a command line option to set a refresh rate of the OS cached metrics in Linux

[Thomas Stuefe]

On Mon, 31 Oct 2022 13:27:13 GMT, Olga Mikhaltsova <omikhaltcova at openjdk.org> wrote:

> I would like to add a new command line product option:
> -XX:OsCachedMetricsRefreshRate=value, -
> where a value is times per second and is in the range [1; 1000000000].
> 
> It substitutes the hardcoded timeout of 20 ms between re-readings of the OS cached metrics introduced in [JDK-8232207](https://bugs.openjdk.org/browse/JDK-8232207) and allows to set this timeout (as a refresh rate) by a user at the launch time.
> 
> This option will be available only on Linux.
> 
> It can be used as followed:
> java -XX:OsCachedMetricsRefreshRate=100 MyApp

Does this really have to be a product switch? The JBS issue sounds like it is not even clear if polling the metrics is actually the culprit. How about a debug-only switch, or at least a diagnostic product switch?

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PR: https://git.openjdk.org/jdk/pull/10918