Garbage Collection

Garbage collection (GC) is an automatic memory management technique in which a runtime system reclaims memory occupied by objects that are no longer reachable by a program. Unlike C or C++, where programmers manually allocate and free memory, garbage-collected languages like Java, Python, and Haskell delegate this responsibility to the runtime. The trade-off is predictability: garbage collection eliminates use-after-free errors and memory leaks caused by programmer omission, but introduces pause times that can destabilize latency-sensitive systems.

The design space of garbage collectors is vast. Mark-and-Sweep algorithms trace reachable objects; Reference Counting reclaims memory immediately when the last reference disappears; generational collectors exploit the empirical observation that most objects die young. Each strategy embodies a different theory about the lifetime distribution of program data — and each fails catastrophically when that theory does not match the workload.