Introduction to Programming

Object age and generations

The basic GC algorithm determines how old each object is. The term age refers to the number of collection cycles the object has survived. When JVM starts, the heap is empty and is divided into three sections: young generation, old or tenured generation, and humongous regions for holding the objects that are 50% the size of a standard region or larger.

The young generation has three areas, an Eden space and two survivor spaces, such as Survivor 0 (S0) and Survivor 1 (S1).  The newly created objects are placed in Eden. When it is filling up, a minor GC process starts. It removes the un-referred and circular referred objects and moves others to the S1 area. At the next minor collection, S0 and S1 switch roles. The ...