Python: Essential Reference, Third Edition

gc

The gc module provides an interface for controlling the garbage collector used to collect cycles in objects such as lists, tuples, dictionaries, and instances. As various types of container objects are created, they’re placed on a list that’s internal to the interpreter. Whenever container objects are deallocated, they’re removed from this list. If the number of allocations exceeds the number of deallocations by a user-definable threshold value, the garbage collector is invoked. The garbage collector works by scanning this list and identifying collections of objects that are no longer being used but haven’t been deallocated due to circular dependencies. In addition, the garbage collector uses a three-level generational scheme in which objects ...