RFR: JDK-8261034: improve jcmd GC.class_histogram to support parallel [v7]

[Lin Zang]

On Sun, 25 Apr 2021 12:44:09 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   improve jcmd GC.class_histogram to support parallel
>
> still waiting for pr #2261

Hi @Hamlin-Li @plummercj, @sspitsyn 
I think maybe this PR can be pushed now because in  #2261, we finally decided to not expose `parallel=` option for `jmap -dump`.
Do you think it is reasonable?

Thanks,
Lin

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

PR: https://git.openjdk.java.net/jdk/pull/2379