What is uncommitted unused memory?
This is actually an enhancement on a previous feature release in Java 11, the Z Garbage Collector (ZGC), which is a scalable low-latency garbage collector. The ZGC adds a small pause before the heap memory cleanup.
This results in the ZGC not returning uncommitted memory to the operating system, even when the memory has been unused for a long time. This is a big issue of concern for devices with a small memory footprint such as IoT and microchips.
Further Reading
JEP 351: ZGC: Uncommit Unused Memory
