How does the JVM manage memory when running the garbage collector during program execution?

The JVM manages memory through several regions, the main ones being Heap and Stack. The Garbage Collector (GC) is responsible for automatically freeing memory occupied by objects that are no longer in use.

When the JVM runs the garbage collector, it performs the following steps:

1. Identifying unreachable objects: The GC analyzes objects in the heap, starting from root references (such as local variables in the stack, static fields), and marks all objects that can be reached.
2. Freeing memory: Objects that cannot be reached are considered garbage, and their memory is freed.
3. Memory compaction (in some algorithms): to avoid fragmentation, remaining objects may be moved closer together.

Garbage collection can be triggered automatically when a certain memory usage threshold is reached or manually via the System.gc() call, although the latter does not guarantee immediate execution.

Example: when creating a large number of objects in a loop, the JVM periodically runs GC to free memory from objects that are no longer needed, preventing heap overflow.