The Garbage-First (G1) collector is a server-style garbage collector, targeted for multi-processor machines with large memories. It meets garbage collection (GC) pause time goals with a high probability, while achieving high throughput. The G1 garbage collector is fully supported in Oracle JDK 7 update 4 and later releases. The G1 collector is designed for applications that:
Can operate concurrently with applications threads like the CMS collector.
Compact free space without lengthy GC induced pause times.
Need more predictable GC pause durations.
Do not want to sacrifice a lot of throughput performance.