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

[Alan Bateman]

On Mon, 30 Jun 2025 15:08:25 GMT, David Beaumont <duke at openjdk.org> wrote:

>> Initial benchmark to capture at least some comparative measures of ImageReader performance.
>> 
>> Current results on my laptop:
>> 
>> Benchmark                                         Mode  Cnt   Score    Error  Units
>> NewImageBenchmark.warmCache_CountAllNodes         avgt    5   0.785 ±  0.140  ms/op
>> NewImageBenchmark.coldStart_CountOnly               ss    5  34.051 ± 17.662  ms/op
>> NewImageBenchmark.coldStart_InitAndCount            ss    5  31.006 ±  9.674  ms/op
>> NewImageBenchmark.coldStart_LoadJavacInitClasses    ss    5   3.752 ±  6.873  ms/op
>> 
>> The upcoming changes to ImageReader should show significant improvements to these results.
>
> 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?

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/26044#discussion_r2176636106