Having recently upgraded to 7.8.1 on all our clusters , we are seeing changed JVM heap usage.
Our max heap usage seems to never go above around 19 GB , no matter what happens in the cluster. Same pattern on all nodes.
We upgraded from 7.6.2 but after upgrade we have started seeing long GC's again, which has not happened in a long time on 7.6.2. GC's in the 5-28 sec range , which is bad for us.
We are wondering with a 31 GB heap on 7.8.1 why it doesnt seem to utilize all available heap. It seems like quite a big part of the heap is reserved.
This is typical over 24 hours.