RFR: 8269032: Stringdedup tests are failing if the ergonomically select GC does not support it

[Per Liden]

On Sun, 27 Jun 2021 01:38:24 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change to the string deduplication tests' handling of an
> ergonomically chosen GC.  They were assuming G1 would be chosen in that
> case, but that's wrong of course.  The test machine might not be a server
> class machine, or G1 might not be included in the build.
> 
> Each test now has a second test declaration comment for handling the case
> where no GC is specified by the jtreg invocation.  This second declaration
> will force the use of G1 by the test if G1 is supported by the VM.
> 
> I looked into trying to be more clever and selecting a different GC if G1 is
> not supported by the VM, but that ended up making the tests a lot more
> messy, and doesn't seem like that important a use-case at this time.  A
> better long-term solution would be to make all the GCs (except Epsilon)
> support string deduplication, so we don't care which GC gets ergonomically
> chosen.  But that's not happening today.
> 
> Testing:
> Ran the string deduplication tests with various configurations: (1)
> explicitly use G1 (2) no explicit GC, (3) no explicit GC with
> -XX:+NeverActAsServerClassMachine.

test/hotspot/jtreg/gc/stringdedup/TestStringDeduplicationAgeThreshold.java line 30:

> 28:  * @summary Test string deduplication age threshold
> 29:  * @bug 8029075
> 30:  * @requires vm.gc == "G1" | vm.gc == "Shenandoah"

I think this should be `@requires vm.gc.G1` and it should pass `-XX:+UseG1GC`to the test, which it appends to the list of arguments for the JVM that will be spawned.

test/hotspot/jtreg/gc/stringdedup/TestStringDeduplicationAgeThreshold.java line 44:

> 42:  * @bug 8029075
> 43:  * @requires vm.gc == "null" & vm.gc.G1
> 44:  * @library /test/lib

... and same here, this should be `@requires vm.gc.Shenandoah` and it should pass `-XX:+UseShenandoahGC`to the test, which it appends to the list of arguments for the JVM that will be spawned.

Of course, same comments apply to all tests.

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PR: https://git.openjdk.java.net/jdk/pull/4603