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I'm trying to pickle instance of my cellular automata class, but I get this error:
RuntimeError: maximum recursion depth exceeded while calling a Python object
My cellular automata consist from list of cells (and bunch of other things) where each cell has pointer to it's neighbours. In this particular CA, there is 256 cells. Now, I know that pickler should be able to recognise already pickled objects.
From docs:
*The pickle module keeps track of the objects it has already serialized, so that later references to the same object won’t be serialized again.
So I don't really know, why I exceeding max recursion depth.
I think that maybe pickler does depth-first pickling, so that it first follow pointers, exceed recursion stack and then raise exception. I know I can extend maximum recursion depth with sys.setrecursionlimit(), but I don't consider that good nor scalable solution.
First question: Does pickler depth-first pickling?
Second question: Any idea how to prevent this exception?
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The maximum recursion depth in Python is 1000. You can change the limit by calling sys. setrecursionlimit() method.
Due to this, the recursion limit of python is usually set to a small value (approx, 10^4). This means that when you provide a large input to the recursive function, you will get an error. This is done to avoid a stack overflow. The Python interpreter limits the recursion limit so that infinite recursions are avoided.
Try increasing the recursion limit ( sys. setrecursionlimit ) or re-writing your code without recursion. Return the current value of the recursion limit, the maximum depth of the Python interpreter stack. This limit prevents infinite recursion from causing an overflow of the C stack and crashing Python.
The Python interpreter limits the depths of recursion to help avoid infinite recursions, resulting in stack overflows. By default, the maximum depth of recursion is 1000 .
So, as @ExP said, pickler does depth-first pickling which causes recursion exceeded exception. Anyway, I found solution to this issue here bugs.python.org. That means for python 3.1 pickler works even on recursive data such as graphs for example.
There is also little less elegant solution which takes a lot more time to pickle some recursive data, but it's simple (just a matter of few lines of code). Link here.
As it seems, it's probably time to start slowly moving towards the python3. Hope that someone find this answer usefull.
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