>the JVM _NEVER_ returns memory to the os That may (or may not) be true of the GC heap, but the GC heap is only one consumer of JVM memory allocations. I don't

>the JVM _NEVER_ returns memory to the os That may (or may not) be true of the GC heap, but the GC heap is only one consumer of JVM memory allocations. I don't know enough to confirm one way or another. Speaking from experience, OpenJ9's JIT compiler aggressively returns transient compilation memory back to the operating system.