RFR: 8157023: Integrate NMT with JFR [v4]

[Markus Grönlund]

On Tue, 6 Dec 2022 16:42:54 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

>> Please review this enhancement to include NMT information in JFR recordings.
>> 
>> **Summary**
>> Native Memory Tracking summary information can be obtained from a running VM using `jcmd` if started with `-XX:NativeMemoryTracking=summary/detail`. Using `jcmd` requires you to run a separate process and to parse the output to get the needed information. This change adds JFR events for NMT information to enable additional ways to consume the NMT data.
>> 
>> There are two new events added:
>> * _NativeMemoryUsage_ - The total native memory usage.
>> * _NativeMemoryUsagePart_ - The native memory usage for each component.
>> 
>> These events are sent periodically and by default the interval is 1s. This can of course be discussed, but that is the staring point. When NMT is not enabled on events will be sent.
>> 
>> **Testing**
>> * Added a simple test to verify that the events are sent as expected depending on if NMT is enabled or not.
>> * Mach5 sanity testing
>
> Stefan Johansson has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Rename the files
>  - Renaming and updating comments
>  - tstuefe review - no rename

test/jdk/jdk/jfr/event/runtime/TestNativeMemoryUsageEvents.java line 97:

> 95:     private static void generateEvents(Recording recording) throws Exception {
> 96:         // Enable the two types of events for "everyChunk", it will give
> 97:         // an event att the beginning of the chunk as well as the end.

"att" -> "at"

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PR: https://git.openjdk.org/jdk/pull/11449