Garbage Collection

Go 16 Sep 2026 5 min read

Go sync.Pool Items Can Disappear Across Garbage Collection

A value placed in a Go sync.Pool is not guaranteed to remain there until a later Get. The runtime may remove pooled items automatically, so the pool acts as a reuse opportunity rather than durable storage. That property shapes both the performance profile and the correctness boundary of sync.Pool. Code can benefit when an object survives long enough to be reused, but it must remain correct when every Get behaves as if no prior item were available.

Golang Memory

Go 16 Sep 2026 4 min read

Go Runtime Finalizers Delay Object Reclamation

A Go object with a finalizer is not reclaimed when the garbage collector first determines that it is unreachable. The runtime must retain the object for the finalizer call, and reclamation can occur only after a later collection finds the object unreachable again. That behavior makes runtime.SetFinalizer materially different from ordinary garbage collection. It adds an asynchronous lifecycle phase between loss of application reachability and memory reclamation. Finalization temporarily restores reachability runtime.SetFinalizer(obj, f) associates f with obj. When the collector detects an unreachable object with that association, it clears the association and arranges a call to f(obj).

Golang Runtime

Software Engineering 13 Sep 2026 7 min read

Garbage Collection Does Not Close External Resources

An object can become unreachable while a file descriptor, socket, database transaction, or operating-system lock associated with it still has a meaningful external lifetime. Garbage collection can reclaim managed memory after reachability disappears. It does not, by that fact alone, perform the protocol operation that releases an external resource. The distinction is structural. A collector reasons about references inside a managed heap. A resource such as a file descriptor is an entry maintained by the operating system, and a database transaction is state maintained by another component. Their release semantics come from APIs and protocols outside the collector’s reachability model.

Software Engineering Resource Management

Python 02 Sep 2026 8 min read

Weak References in Python: Caches, Object Lifetimes, and Cleanup

A normal Python reference keeps an object alive. That is usually exactly what you want: if a dictionary contains an object, the object should remain available while the dictionary needs it. Some infrastructure has a different requirement. A cache, registry, or metadata table may want to refer to an object without becoming the reason that object stays alive forever. Python’s weakref module provides references and containers for that ownership model.

Python weakref