Understanding the G1 garbage collector

The previous GC implementations include the Serial GC, Parallel GC, and Concurrent Mark-Sweep (CMS) collector. They divide the heap into three sections—young generation, old or tenured generation, and humongous regions for holding the objects that are 50% of the size of a standard region or larger. The young generation contains most of the newly created objects; this is the most dynamic area because a majority of the objects are short-lived and soon (as they age) become eligible for collection. The term age refers to the number of collection cycles the object has survived. The young generation has three collection cycles— an Eden space and two survivor spaces, such as survivor 0 (S0) and survivor 1 (S1). The objects are moved through them (according to their age and some other characteristics) until they are eventually discarded...