-------- Forwarded Message --------
Subject: Re: RFR: 8332124: Jcmd processing should accept the "help" sub
option as command argument [v2]
Date: Tue, 25 Jun 2024 13:30:04 -0700
From: Laurence Cable <larry.ca...@oracle.com>
To: serviceability-dev@openjdk.org
what about '*jcmd <pid> help <cmd>*' not a great deal of additional code
for the 'help' jcmd to delegate to the target jcmd?
/a/nd jcmd already supports "help" w/o a target argument, so this
pattern is a natural extension, and one which other toolsets have adopted!
- Larry
On 6/25/24 10:15 AM, Kevin Walls wrote:
On Tue, 25 Jun 2024 13:55:32 GMT, Sonia Zaldana Calles<szald...@openjdk.org>
wrote:
Hi all,
This PR addresses [8332124](https://bugs.openjdk.org/browse/JDK-8332124) enabling jcmd to
accept "help" as an argument to subcommands.
Testing:
- [x] Verified running `jcmd 4711 VM.metaspace help` works along with other
subcommands.
- [x] Added test case passes.
Thanks,
Sonia
Sonia Zaldana Calles 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 three additional
commits since the last revision:
- Merge branch 'openjdk:master' into JDK-8332124
- Adding test case for suboptions with trailing spaces and adding null
terminator to reordered command
- 8332124: Jcmd processing should accept the "help" sub option as command
argument
I could benefit from this, I think it's natural to sometimes want to check the
help after you've started typing, so I like the idea. But can it actually
clash with any other usage?
e.g. "help" can be a filename. We are making the filename "help" unusable.
Maybe not a big deal to most people, but we do need to make this clear.
jcmd PID Thread.dump_to_file help
...used to create a file "help", and now does not?
Compiler.directives_add takes a filename and would accept "help".
GC.heap_dump used to create a dump file called "help".
jcmd 7537 VM.set_flag help
..could have been a clash if we had such a VM flag (not likely...).
I don't mean to labour artificial or uncommon cases, but we do want this to be
clearly specified. Maybe this is still OK with the right hints (somewhere?)
about the filenames that are now not possible to read or create.
Any thoughts on if
jcmd PID command -help
or
jcmd PID command --help
..should work, or could work? Additionally, or instead? Maybe they are better, as users
relying on files called "-help" would be really uncommon (and would be inviting
problems!).
Good to ignore the trailing whitespace.
Not obvious whether trailing extra text should be ignored or cause an error.
e.g.
jcmd 7537 VM.stringtable help nonsense
7537:
java.lang.IllegalArgumentException: Unknown argument 'help' in diagnostic
command.
..where I guess it's not the "help" which is unknown. Is the user better served by just
giving the help and ignoring the additional "nonsense"?
-------------
PR Review:https://git.openjdk.org/jdk/pull/19776#pullrequestreview-2139311805
