RFR: JDK-8260571: Add PrintMetaspaceStatistics to print metaspace statistics upon VM exit

[Ioi Lam]

On Mon, 1 Feb 2021 20:57:22 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Looks good to me.
>
> I agree with Thomas.  I think there's a way to make UL not print the decorations with these Print<Stuff>AtExit, but otherwise the decorations are noisy.  We purposefully didn't not translate the options that print a lot of output to UL because the decorations and the timestamps aren't interesting. eg. PrintSystemDictionaryAtExit or PrintInterpreter.  If someone wants to change this so that these options suppress decorations and translate to UL, we can change metspace printing at exit also.  As a diagnostic flag, there isn't any promise of it's longevity in the code. ie. we can change it if we want.

> I agree with Thomas. I think there's a way to make UL not print the decorations with these PrintAtExit, but otherwise the decorations are noisy. We purposefully didn't not translate the options that print a lot of output to UL because the decorations and the timestamps aren't interesting. eg. PrintSystemDictionaryAtExit or PrintInterpreter. If someone wants to change this so that these options suppress decorations and translate to UL, we can change metspace printing at exit also. As a diagnostic flag, there isn't any promise of it's longevity in the code. ie. we can change it if we want.

OK, I withdraw my objection.

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PR: https://git.openjdk.java.net/jdk/pull/2283