RFR: 8352107: Allow jtreg test cases to query test VM properties

[Ioi Lam]

On Tue, 18 Mar 2025 19:21:11 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> This PR tries to cut down the use of `WhiteBox` in the HotSpot test cases. It modifies `VMProps` to save the set of VM properties into a file called "vm.properties" under Jtreg's work directory. The new API `jdk.test.lib.VMPropsGetter` loads the properties from this file to pass onto individual test cases.
>> 
>> See `getJtregWorkDir()` for the code that figures out the work directory. It assumes that `VMProps` and all test cases are always executed under
>> 
>> - `workDir/scratch/` ; or
>> - `workDir/scratch/[0-9]+/` 
>> 
>> This is probably not the right thing to do. I would be better for Jtreg to pass the location of the work directory to the test cases, with a command-line options like `-Djtreg.work.dir=<dir>`.
>> 
>> To show the benefit of this PR, I modified a few test cases to remove their use of WhiteBox.
>
> Changes requested by lmesnik (Reviewer).

Per @lmesnik , this RFE will not work. Closing this PR as will-not-fix.

Alternative RFE: [JDK-8352528 - Move CDS WhiteBox APIs to jdk.internal.test.cds.WhiteBox](https://bugs.openjdk.org/browse/JDK-8352528)

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PR Comment: https://git.openjdk.org/jdk/pull/24071#issuecomment-2741093037