RFR: 8259070: Add jcmd option to dump CDS [v3]

[Yumin Qi]

On Wed, 10 Mar 2021 04:28:04 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Yumin Qi has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix white space in CDS.java
>
> src/java.base/share/classes/jdk/internal/misc/CDS.java line 256:
> 
>> 254: 
>> 255:             // Do not take parent env which will cause dumping fail.
>> 256:             Process proc = Runtime.getRuntime().exec(cmds.toArray(new String[0]),
> 
> Could you explain why the parent's env variables will cause dumping to fail?

I found jtreg env will be brought in to the children env which is not needed in this case. Add comment.

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PR: https://git.openjdk.java.net/jdk/pull/2737