RFR: JDK-8327769: jcmd GC.heap_dump without options should write to location given by -XX:HeapDumpPath, if set [v6]

[Matthias Baesken]

On Fri, 15 Mar 2024 08:35:56 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> Currently jcmd command GC.heap_dump only works with an additionally provided file name.
>> Syntax : GC.heap_dump [options] <filename>
>> 
>> In case the JVM has the XX - flag HeapDumpPath set, we should support an additional mode where the <filename> is optional.
>> In case the filename is NOT set, we take the HeapDumpPath (file or directory);
>> 
>> new syntax :
>> GC.heap_dump [options] <filename> .. has precedence over second option
>> GC.heap_dump [options] …in case -XX: HeapDumpPath=p is set
>> 
>> This would be a simplification e.g. for support cases where a filename or directory is set at JVM startup with -XX: HeapDumpPath=p and writing to the path is intended/recommended for usage also in the jcmd case.
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   rename dump_to_heapdump_path

Hi Chris, thanks for the comments-

> Also, if you are cleaning up this text, I would suggest changing "is on" to "is enabled". Same for HeapDumpGzipLevel below.

I changed the two locations.
btw. seems we have more of those in globals.hpp .
See the comments related to PrintNMTStatistics and LogFile  (where the "is on" is used as well).

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PR Comment: https://git.openjdk.org/jdk/pull/18190#issuecomment-1999211132