Those memory footprint improvements in JDK 18

[charlie hunt]

Hi Stefan,

The graph Thomas shows in his blog is the GC part of the NMT output 
which does not include metadata.

The GC part of NMT output includes native memory allocated on behalf of 
the GC itself such as a card table or remembered set .. those things 
that GC needs to do its work. The native memory allocated for the Java 
heap are in the "Java Heap" section of the NMT output. Class metadata is 
in the "Class" section of the NMT output.

There is a "Native Memory Tracking Memory Categories" table that lists 
the sections / categories reported by NMT and a description of each at:
https://docs.oracle.com/en/java/javase/17/troubleshoot/diagnostic-tools.html#GUID-5EF7BB07-C903-4EBD-A9C2-EC0E44048D37

hths,

Charlie

On 5/6/22 2:13 PM, Stefan Reich wrote:
> I'm right now just trying to get over how amazing this graph is: 
> https://tschatzl.github.io/2022/03/14/jdk18-g1-parallel-gc-changes.html
>
> 35-40% savings in memory use just by using JDK 18??? Who would have 
> expected such a major improvement after 17 iterations of the language!
>
> Just so I'm sure I'm reading it correctly... the graph basically shows 
> the Java heap's memory footprint in terms of committed native memory. 
> Right?
>
> So it would include Eden, tenured generations, humongous objects, but 
> not metadata and code. Is that correct?
>
> Basically tell me how much I should celebrate this. lol
>
> I did switch another small, pretty crammed (8 GB RAM) server over to 
> JDK 18 and it does feel like there's a lot more memory available on it 
> now and everything is a lot faster too.
>
> Cheers
> Stefan
>
> -- 
> == Gaz.AI <http://Gaz.AI> ==
>
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