RFR: 8318026: jcmd should provide access to low-level JVM debug information [v7]

[Thomas Stuefe]

On Tue, 5 Mar 2024 11:31:13 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> Introduce the jcmd "VM.debug" to implement access to a useful set of the established debug.cpp utilities, with "jcmd PID VM.debug subcommand ...".
>> 
>> Not recommended for live production use.  Calling these "debug" utilities, and not including them in the jcmd help output, is to remind us they are not general customer-facing tools.
>
> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Test update

Hi Kevin,

> 
> (If you find existing jcmds a mess, feel free to suggest changes as appropriate.)

you touch on a problem here, and why I think adding commands should be done more carefully (and I am guilty of adding commands too). 

Once these commands are rolled out, they find themselves in blogs, knowledge bases, scripts that are reused for different JDK releases, and so on. It is difficult to change them post-release. That is why good names are important.

Cheers, Thomas

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PR Comment: https://git.openjdk.org/jdk/pull/17655#issuecomment-1980807020