Does GC release back memory to OS?

Question

When the garbage collector runs and releases memory does this memory go back to the OS or is it being kept as part of the process. I was under the strong impression that the

Answer 1

If you use the G1 collector and call System.gc() occasionally (I do it once a minute), Java will reliably shrink the heap and give memory back to the OS.

Since Java 12, G1 does this automatically if the application is idle.

I recommend using these options combined with the above suggestion for a very compact resident process size:

-XX:+UseG1GC -XX:MaxHeapFreeRatio=30 -XX:MinHeapFreeRatio=10

Been using these options daily for months with a big application (a whole Java-based guest OS) with dynamically loading and unloading classes - and the Java process almost always stays between 400 and 800 MB.