RFR: 8292329: Enable CDS shared heap for zero builds [v2]

[Erik Joelsson]

On Tue, 23 Aug 2022 16:49:01 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> ZERO uses UseSerialGC by default. When we dump the default CDS archive during the build process, it fails to dump the shared heap (which requires G1GC).
>> 
>> The fix is to force -XX:+UseG1GC when dumping the default CDS archive during the build process.
>> 
>> Speed up:
>> 
>> (Before)
>> $ perf stat -r 40 ./images/jdk/bin/java -version
>> 0.018080 +- 0.000388 seconds time elapsed ( +- 2.15% )
>> 
>> (After)
>> $ perf stat -r 40 ./images/jdk/bin/java -version
>> 0.011986 +- 0.000205 seconds time elapsed ( +- 1.71% )
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   @shipilev review comments

Marked as reviewed by erikj (Reviewer).

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

PR: https://git.openjdk.org/jdk/pull/9984