Are ratios between spaces/generations in the Java Heap constant?

Question

I have read this article about virtual machine garbage collection tuning to understand the java garbage collector better. Each space has a Virtual heap space area

Answer 1

I think you are referring to GC Ergonomics and the Adaptive Size Policy

• a feature of the Hotspost GC that automatically adapts the sizes of the generations at runtime based on the current allocation behavior of the running application.
• This feature is ON by default and controls/adapts the size of the generations at runtime.
• in fact, some of the GC parameters will be ignored if you do not disable Adaptive Size policy, eg. -XX:SurvivorRatio=.

You can disable the Adaptive Size Policy by using the -XX:-UseAdaptiveSizePolicy. Once you disabled the AdaptiveSizePolicy, the GC will respect the initial size of the generations as specified by your startup parameters (e.g. -Xms, -Xmx, -XX:MaxNewSize=,-XX:NewSize=, -XX:SurvivorRatio=) and they will remain constant.

You can find more on Adaptive Size policy in UseAdaptiveSizePolicy and other jvm opts.