GarbageCollectionTuning

Garbage collection is an automatic memory management technique used by many high-level programming languages to reclaim memory that is no longer in use. It helps prevent memory leaks and dangling references by tracking object reachability rather than requiring manual deallocation. While it reduces programmer burden, it can introduce execution pauses and trade-offs in performance.

Most garbage collectors are built around the concept of tracing reachability. They determine which objects can still be accessed from roots such as the call stack or global references. Classic approaches include tracing collectors, such as mark-and-sweep and mark-compact, as well as reference counting, which tracks how many references exist to an object and frees it when the count reaches zero. Modern systems often combine techniques to balance throughput and pause times.

Generational collection is a common optimization. It rests on the observation that most objects die young, so the heap is partitioned into young and old generations. Collections in the young generation are frequent and fast, while objects that survive are promoted to the older generation for less frequent, more thorough collections. This approach reduces overall work by concentrating effort where it is most effective.

Concurrency and incremental techniques aim to reduce pause times by performing portions of the garbage-collection work while the program continues to run, sometimes stopping briefly only when necessary. Real-time or low-latency environments may employ specialized collectors designed to provide predictable pauses.

In practice, garbage collection is a central feature of languages such as Java, C#, and JavaScript, where it shapes performance, memory footprint, and responsiveness. Other languages, like C or C++, typically rely on manual memory management or optional GC libraries. The choice and tuning of a GC system depend on application requirements for throughput, latency, and memory usage.