“Island of isolation” of Garbage Collection

Question

Could anyone please explain the concept of Island of isolation of Garbage Collection?

Answer 1

The thing to keep in mind is that objects are only collected if they are referenced, either directly or indirectly, from a GC root object (threads, current local variables, static variables etc). If two (or more) objects reference each other, but are not referenced from a root, then they are eligible for garbage collection.