large size of [Ljdk.internal.vm.FillerElement in jmap histo

[Thomas Schatzl]

Hi,

On 25.07.24 18:10, shanghe chen wrote:
> Thanks for the helpful infomation! Yeah I am trying to understand this. 
> it seems after jdk21 the int[] is turned to FillerArray (or 
> FillerElement?) and I am not sure if it count into the JMX bean for 
> monitoring the Oldgen size of G1GC or not though.

   more information about the rationale for their introduction:

https://tschatzl.github.io/2022/09/26/jdk-vm-internal-fillerarray.html

Answering your question, they represent dead objects/free space within 
regions. However since they are not allocatable into by the application 
and only drive reclamation heuristics, they are considered as part of 
"used" in MemoryMXBeans.

This is the same behavior as the previous int[] arrays.

Hth,
   Thomas