Integrated: 8259070: Add jcmd option to dump CDS

[Yumin Qi]

On Fri, 26 Feb 2021 00:03:40 GMT, Yumin Qi <minqi at openjdk.org> wrote:

> Hi, Please review
> 
>   Added jcmd option for dumping CDS archive during application runtime. Before this change, user has to dump shared archive in two steps: first run application with
>   `java -XX:DumpLoadedClassList=<classlist> .... `  
>  to collect shareable class names and saved in file `<classlist>` , then 
>   `java -Xshare:dump -XX:SharedClassListFile=<classlist> -XX:SharedArchiveFile=<archivefile> ...`
>   With this change, user can use jcmd to dump CDS without going through above steps. Also user can choose a moment during the app runtime  to dump an archive.
>    The bug is associated with the CSR: https://bugs.openjdk.java.net/browse/JDK-8259798 which has been approved.
>    New added jcmd option:
>    `jcmd <pid or AppName> VM.cds static_dump <filename>`
>    or
>     `jcmd <pid or AppName> VM.cds dynamic_dump <filename>`
>   To dump dynamic archive, requires start app with newly added flag `-XX:+RecordDynamicDumpInfo`, with this flag, some information related to dynamic dump like loader constraints will be recorded. Note the dumping process changed some object memory locations so for dumping dynamic archive, can only done once for a running app. For static dump, user can dump multiple times against same process. 
>    The file name is optional, if the file name is not supplied, the file name will take format of `java_pid<number>_static.jsa` or `java_pid<number>_dynamic.jsa` for static and dynamic respectively. The `<number>` is the application process ID.
> 
>   Tests: tier1,tier2,tier3,tier4
> 
> Thanks
> Yumin

This pull request has now been integrated.

Changeset: e7cbeba8
Author:    Yumin Qi <minqi at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/e7cbeba8
Stats:     857 lines in 23 files changed: 783 ins; 58 del; 16 mod

8259070: Add jcmd option to dump CDS

Reviewed-by: ccheung, iklam, mli

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