RFR: 8322811: jcmd System.dump_map help info has conflicting statements

[Kevin Walls]

On Mon, 10 Jun 2024 17:08:58 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> @dholmes-ora this is one of yours.
>> 
>> This was a tad annoying to fix (fix is simple though), since the jcmd framework has no good way to allow for default parameters that are not used literally. E.g. in this case, the real value for the file name will contain the process pid, which of course cannot be hard-coded.
>> 
>> New output:
>> 
>> 
>> Syntax : System.dump_map [options]
>> 
>> Options: (options must be specified using the <key> or <key>=<value> syntax)
>>         -H : [optional] Human readable format (BOOLEAN, false)
>>         -F : [optional] file path (STRING, vm_memory_map_<pid>.txt)
>
> src/hotspot/share/services/diagnosticCommand.cpp line 1211:
> 
>> 1209:   } else {
>> 1210:     name = _filename.value();
>> 1211:   }
> 
> This code should be considering if a default it specified or not, in case the specified value is identical to what is contained in `default_filename`.  With the current solution, if the user literally specifies vm_memory_map_<pid\>.txt, the <pid> part will be expanded to the actual pid. See how [JDK-8323546](https://bugs.openjdk.org/browse/JDK-8323546) handled this.

Oops yes should definitely be using _filename.is_set() rather than strcmp.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/19596#discussion_r1634365367