Garbage-First Garbage Collector (G1GC)
- is designed for applications running on multi-processor machines with large memory space
- it’s available since JDK7 Update 4 and in later releases
- will replace the CMS collector since it’s more performance efficient.
Unlike other collectors, the G1 collector partitions the heap into a set of equal-sized heap regions, each a contiguous range of virtual memory. When performing garbage collections, G1 shows a concurrent global marking phase (i.e. phase 1 known as Marking) to determine the liveness of objects throughout the heap.
After the mark phase is completed, G1 knows which regions are mostly empty. It collects in these areas first, which usually yields a significant amount of free space (i.e. phase 2 known as Sweeping). It is why this method of garbage collection is called Garbage-First.
To enable the G1 Garbage Collector, we can use the following argument:
java -XX:+UseG1GC -jar Application.java