RFR: 8370050: Shenandoah: Obsolete ShenandoahPacing option

[William Kemper]

On Fri, 17 Oct 2025 04:37:07 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> ShenandoahPacing was removed in this release (26). Rather than have the JVM refuse to start if this option is given, it should give a warning that the option is removed and is ignored and will reject the option in JDK27.
>> 
>> Testing:
>> 
>> [0] % ./build/linux-x86_64-server-release/jdk/bin/java -XX:+UseShenandoahGC -XX:+UnlockExperimentalVMOptions -XX:+ShenandoahPacing --version
>> OpenJDK 64-Bit Server VM warning: Ignoring option ShenandoahPacing; support was removed in 26.0
>
> src/hotspot/share/runtime/arguments.cpp line 551:
> 
>> 549:   { "ZMarkStackSpaceLimit",         JDK_Version::undefined(), JDK_Version::jdk(25), JDK_Version::undefined() },
>> 550:   { "G1UpdateBufferSize",           JDK_Version::undefined(), JDK_Version::jdk(26), JDK_Version::jdk(27) },
>> 551:   { "ShenandoahPacing",             JDK_Version::jdk(25), JDK_Version::jdk(26), JDK_Version::jdk(27) },
> 
> Nit: you didn't actually deprecate the option in 25 so this should have been left as `undefined()`.

Sorry, I missed this comment earlier. We sort of did deprecate it in 25 through this change: https://github.com/openjdk/jdk25u/pull/321.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27859#discussion_r2461147097