RFR: 8334492: DiagnosticCommands (jcmd) should accept %p in output filenames and substitute PID [v3]

[Leonid Mesnik]

On Wed, 17 Jul 2024 19:59:10 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 one additional commit since the last revision:
> 
>   Updates based on feedback

Changes requested by lmesnik (Reviewer).

src/hotspot/share/code/codeCache.cpp line 1791:

> 1789: 
> 1790: #ifdef LINUX
> 1791: void CodeCache::write_perf_map(const char* filename, outputStream* out) {

I don't think that it is a right place ti expand arguments here. I think it is more consistent to do it in diagnosticCommand.cpp for any jcmd command.  So this logic might be the same for any _filename processing. Moreover it would be better be add 'FileArgument' like 'MemorySizeArgument' that correctly parse patterns like %p for all file arguments, used be all commands and be extensible for new macroses if needed.

test/jdk/sun/tools/jcmd/TestJcmdPIDSubstitution.java line 32:

> 30:  * @modules java.base/jdk.internal.misc
> 31:  *          java.management
> 32:  * @run main/othervm TestJcmdPIDSubstitution

Why othervm is needed here?  I suggest to add driver mode instead.

test/jdk/sun/tools/jcmd/TestJcmdPIDSubstitution.java line 59:

> 57:         do {
> 58:             path = Paths.get("myfile%d".formatted(pid));
> 59:         } while(Files.exists(path));

Why this do/while loop is needed? Each test should have it's own empty scratch directory.

-------------

PR Review: https://git.openjdk.org/jdk/pull/20198#pullrequestreview-2184333180
PR Review Comment: https://git.openjdk.org/jdk/pull/20198#discussion_r1681931084
PR Review Comment: https://git.openjdk.org/jdk/pull/20198#discussion_r1681921063
PR Review Comment: https://git.openjdk.org/jdk/pull/20198#discussion_r1681920781