RFR: 8259070: Add jcmd option to dump CDS [v4]

[Yumin Qi]

On Fri, 26 Feb 2021 22:46:07 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Yumin Qi has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - Fix filter more flags to exclude in static dump, add more test cases
>>  - Merge branch 'master' into jdk-8259070
>>  - Fix white space in CDS.java
>>  - Add function CDS.dumpSharedArchive in java to dump shared archive
>>  - 8259070: Add jcmd option to dump CDS
>
> src/hotspot/share/runtime/arguments.cpp line 3525:
> 
>> 3523:       os::free(SharedDynamicArchivePath);
>> 3524:       SharedDynamicArchivePath = nullptr;
>> 3525:     }
> 
> Is this necessary?

When do dynamic dump, we set SharedDynamicArchivePath to the given file name, after that, restore the original value so free the old one to prevent memory leak.

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