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

[Alan Bateman]

On Wed, 31 Jan 2024 14:22:44 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.

This proposal effectively opens a new side channel for debugging with several commands ("events", "find", "findclass",  ...). This will surely end up in troubleshooting recipes and other documentation. For now, the commands look benign but it may be tempting for people to show up with changes that extend this for other things. So I think this feature needs wider review and a CSR should be submitted for this.

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PR Comment: https://git.openjdk.org/jdk/pull/17655#issuecomment-1926365013