Yes, but that’s the point: objects which don’t escape are pretty much all young objects. So by this process the stack captures a significant fraction of the young generation, that young generation never reaches the heap and this is never under consideration by the GC.

Essentially the stack is a form of younggen. It is not as complete (as there are things which must be heap allocated) but because it is, it reduces the benefits of a generational GC… without having much impact on its costs and complexity.

Depending on work load, that competition can be sufficient to make a generational GC net negative.

Thanks for the answer. But is this actual behaviour for the GCs of the JDK? I was certain that at the very least Hotspot makes use of stack allocation as much as possible.

But perhaps the JDK GCs don't care so much about the stack because that is already dealt by the JVM a step prior? In any case, there will likely still be young objects allocated in the heap and this new algorithm might prove useful.

But you can tell I am far from an expert here.