RFR: 8334492: DiagnosticCommands (jcmd) should accept %p in output filenames and substitute PID [v4]

[Sonia Zaldana Calles]

On Fri, 19 Jul 2024 13:51:17 GMT, Sonia Zaldana Calles <szaldana at openjdk.org> wrote:

>> Hi all, 
>> 
>> This PR addresses [8334492](https://bugs.openjdk.org/browse/JDK-8334492) enabling jcmd diagnostic commands that issue an output file to accept the `%p` pattern in the file name and substitute it for the PID. 
>> 
>> This PR addresses the following diagnostic commands: 
>> - [x] Compiler.perfmap 
>> - [x] GC.heap_dump
>> - [x] System.dump_map
>> - [x] Thread.dump_to_file
>> - [x] VM.cds
>> 
>> Note that some jcmd diagnostic commands already enable this functionality (`JFR.configure, JFR.dump, JFR.start and JFR.stop`). 
>> 
>> I propose opening a separate issue to track updating the man page similarly to how it’s done for the JFR diagnostic commands. For example, 
>> 
>> 
>> filename         (Optional) Name of the file to which the flight recording data is
>>                    written when the recording is stopped. If no filename is given, a
>>                    filename is generated from the PID and the current date and is
>>                    placed in the directory where the process was started. The
>>                    filename may also be a directory in which case, the filename is
>>                    generated from the PID and the current date in the specified
>>                    directory. (STRING, no default value)
>> 
>>                    Note: If a filename is given, '%p' in the filename will be
>>                    replaced by the PID, and '%t' will be replaced by the time in
>>                    'yyyy_MM_dd_HH_mm_ss' format.
>> 
>> 
>> Unfortunately, per [8276265](https://bugs.openjdk.org/browse/JDK-8276265), sources for the jcmd manpage remain in Oracle internal repos so this PR can’t address that. 
>> 
>> Testing: 
>> 
>> - [x] Added test case passes. 
>> - [x] Modified existing VM.cds tests to also check for `%p` filenames. 
>> 
>> Looking forward to your comments and addressing any diagnostic commands I might have missed (if any). 
>> 
>> Cheers, 
>> Sonia
>
> Sonia Zaldana Calles has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Adding tests for file dcmd argument
>  - Updates to test case
>  - Adding FileArgument as a diagnostic argument

Hi folks, 

I made some updates. Just wanted to note a few things: 
* I think we can remove `test/jdk/sun/tools/jcmd/TestJcmdPIDSubstitution.java` and the changes to test/hotspot/jtreg/runtime/cds/appcds/jcmd tests. I’ve added a test case for dcmd file argument parsing which is more general. I’ve left the old tests in for reference at the moment. 

* Regarding warnings, I noted we wanted to issue any warnings to the issuer of the dcmd and not the JVM process. However,  in ```diagnosticArgument.cpp```, they are issuing the warnings directly to the JVM process. I tried to stay consistent with how things are done there, but let me know what you think. 

Thanks for the comments!
Sonia

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PR Comment: https://git.openjdk.org/jdk/pull/20198#issuecomment-2239256942