Mastering High Performance with Kotlin

Working principles of the garbage collector

The garbage collection strategy assumes that the developer doesn't explicitly release memory. Instead, the garbage collector (GC) finds objects that aren't being used anymore and destroys them. As GC sees it, there are two types of objects—reachable and unreachable. This principle is based on a set of root objects that are always reachable. An object is a root if it satisfies one of the following criteria:

• Local variables: They are stored in the stack of a thread. When a method, constructor, or initialization block is entered, local variables are created and become unreachable and available for the GC once they exit the scope of the method, constructor, or initialization block.
• Active threads