strange ergonomics GC's

[Matt Bruce]

Hi -



I was wondering if anyone else has come across random Ergonomics GC’s when
their VM is specifically set up to never do Ergonomics GCs.



Here are our settings for VM:



 1. Set our min max heap with -Xmx, -Xms

 2. Set our GC to be -XX:+UseParallelGC

 3. Set perm size via -XX:PermSize=

 4. Set -XX:MaxPermSize

 5. Set -XX:ReservedCodeCache=

 6. Set -XX:InitialCodeCache=

 7. Set -XX:NewSize=

 8. Set -XX:MaxNewSize= (same value as new size)

 9. Set -XX:SurvivorRatio


 We then turn off a bunch of ergonomics via:

 1. -XX:-UseAdaptiveSizePolicy

 2. -XX:-UseAdaptiveGCBoundary

 3. -XX:-UseAdaptiveGCBoundary


The hope is that with all that, we would never see a GC for "Ergonomics".

However, every once in a while, when we have a TON of free memory still

(think Gigabytes of Eden space free, and Gigabytes of old gen free),

the VM will suddenly kick into a really long GC (Ergonomics).


I want to stop that from happening, but I don't know what option I'm

missing so that it won't do that.  There are probably still one or two

pieces of memory that the VM thinks it can toy with, such that it bothers

to do an Ergonomics GC.  Or potentially it’s a bug with the VM.



Many Thanks.


Matt Bruce
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