What is the garbage collector in Java?

In Java, Garbage Collection (GC) is an automatic memory management mechanism used to automatically reclaim memory space occupied by objects that are no longer in use, in order to prevent memory leaks and save memory resources.

During the execution of a Java program, objects created using the “new” keyword are allocated space in the heap memory. When an object is no longer referenced or inaccessible, it becomes garbage. The garbage collector periodically scans the heap memory, identifies these garbage objects, and releases the memory space they occupied, allowing it to be reused.

The working mechanism of GC is implemented through a mark-and-sweep algorithm. Initially, GC will mark all active objects, then clear and release all unmarked objects. This process can be seen as a concurrent process that does not interrupt program execution.

The benefit of garbage collection is that it significantly reduces the amount of manual memory release work for programmers, thus improving development efficiency. However, excessive GC can also cause some performance losses, so it is necessary to configure and optimize it reasonably when using it.