RFR: 8319873: Add windows implementation for jcmd System.map and System.dump_map [v13]

[Kevin Walls]

On Thu, 12 Sep 2024 20:10:45 GMT, Simon Tooke <stooke at openjdk.org> wrote:

>> This is a port of [JDK-8318636](https://github.com/openjdk/jdk/pull/16301) to Windows.
>> 
>> System.map and System.dump_map are implemented using the Windows API and provide roughly the same information in the same format.  Most of the heavy lifting was implemented by @tstuefe in #16301 - this PR adds the Windows implementation and enables the common code for Windows 64 bit.
>>  
>> [Sample output (with NMT enabled)](https://github.com/user-attachments/files/16982072/sample_windows_map.txt)
>
> Simon Tooke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove trailing whitespace

Sorry if I'm holding this up.  The reasoning did get confusing to me.

We are not always good at documenting these commands.  But at some point, somebody among us will hopefully document them, or explain it to somebody who will.  There will need to be explanation of how the outputs differ on Linux and Windows, and how the information can be used.

RSS is on Linux only... No problem, that has a well-understood meaning on *nix systems.

offset?  It's the same as the size of the previous line of output.  Or the sum of sizes if there are multiple lines as part of the same allocation.  It's Windows only.  It's not likely this is more useful on Windows than Linux.  Is it considered missing on Linux, or just not needed?

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PR Comment: https://git.openjdk.org/jdk/pull/20597#issuecomment-2353969950