The garbage collector in Python does not work like that. If an object reaches zero references is destroyed immediately. The only problem is when circular references exist and is in this case when object deletion is delayed until the garbage collector runs the algorithm to detect circular references and delete them. This time is longer depending on the generation in which the object is placed.

Although this is true, there might be a problem in the lines you explain because is not guaranteed to collect garbage containing circular references (see Data Model in the documentation). In this case is important as you state to have an interface to ensure releasing the resources.