RFR: 8361076: Add benchmark for ImageReader in preparation for Valhalla changes [v3]

[David Beaumont]

On Tue, 1 Jul 2025 07:25:35 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> David Beaumont has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Some tidying up relating to the state objects.
>
> test/micro/org/openjdk/bench/jdk/internal/jrtfs/ImageReaderBenchmark.java line 230:
> 
>> 228:     // Created by running "java -verbose:class", throwing away anonymous inner
>> 229:     // classes and anything without a reliable name, and grouping by the stated
>> 230:     // source. It's not perfect, but it's representative.
> 
> I don't think this is maintainable. How useful (or not) is this benchmark if the names of all the internal classes (that will change from release to release) are dropped from this?

Debatable. It's obviously going to scale any results somewhat based on the size of the resources and number of classes. It's kind nice to see "this change removes at least N micro/milli seconds of time spent" since that's a minimum set of classes we expect to always be needed, so any time saved is a lower bound.

I'd say maybe leave it as is for now with a note saying "if this keeps breaking, make the list less fragile".
I'm also assuming this is only run manually, and not a part of any CI pipeline ... so please let me know if I'm wrong about that.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26044#discussion_r2178080151