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Python: Is it possible to have an actual memory leak in Python because of your code?

Since the python garbage collector handles detection of circular references (object A referencing Object B and Object B referencing Object A), I was wondering what could cause a memory leak in python code? Can you provide specific examples of code that would create an inaccessible region of memory that the garbage collector could not handle or is such a thing impossible?

Any examples appreciated !

Answer 1

You can use the gc — Garbage Collector interface module,

gc.garbage:

A list of objects which the collector found to be
unreachable but could not be freed (uncollectable objects). By
default, this list contains only objects with __del__() methods. [1]
Objects that have __del__() methods and are part of a reference cycle
cause the entire reference cycle to be uncollectable, including
objects not necessarily in the cycle but reachable only from it.
Python doesn’t collect such cycles automatically because, in general,
it isn’t possible for Python to guess a safe order in which to run the
__del__() methods. If you know a safe order, you can force the issue by examining the garbage list, and explicitly breaking cycles due to
your objects within the list. Note that these objects are kept alive
even so by virtue of being in the garbage list, so they should be
removed from garbage too. For example, after breaking cycles, do del
gc.garbage[:] to empty the list. It’s generally better to avoid the
issue by not creating cycles containing objects with __del__().
methods, and garbage can be examined in that case to verify that no
such cycles are being created.