RFR: JDK-8327769: jcmd GC.heap_dump without options should write to location given by -XX:HeapDumpPath, if set [v8]

[Chris Plummer]

On Tue, 19 Mar 2024 10:16:42 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>>> If -XX:HeapDumpPath is specified, then it is used as the default
>> 
>> No, the filename set with jcmd GC:heamp_dump  filename   has priority. So we should better keep the current description.
>
> So should I also use  HeapDumpGzipLevel  the same way as HeapDumpPath ? Tehn we have to change the text in globals.hpp for HeapDumpGzipLevel as well because it mentions only the HeapDumpOnOutOfmemoryError case and not the jcmd case .

I actually mentioned  HeapDumpGzipLevel as another reason not to make this change. I'm still not seeing it's value relative to the documentation headaches it causes.

@ansteiner commented that:

> This is really helpful from a support point of view.

I'd like to understand how. It seems to me that the person using the jcmd has a lot more interest in where the file ends up than the person launching the JVM, and can always specify the location with the jcmd. It seems odd to me that the jcmd user would want to rely on HeapDumpPath when they can just specify the path with the jcmd and know for sure where the file is going to end up.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18190#discussion_r1531043688