Reference counting

Question

Reference counting

Accepted Answer

Every Python object has a reference count field. Binding a name or storing in a list increments it; rebinding or deleting decrements it. When the count hits zero, CPython frees the memory right away - no waiting for a garbage collection cycle. The limitation is reference cycles (a -> b -> a): the counts never reach zero even though neither object is reachable, which is why Python also has a cyclic garbage collector on top of reference counting.