What is the maximum recursion depth in Python, and how to increase it?

Question

I have this tail recursive function here:

def recursive_function(n, sum):     if n < 1:         return sum     else:         return recursive_function(n-1, sum+n)  c = 998 print(recursive_function(c, 0)) 

It works up to n=997, then it just breaks and spits out a RecursionError: maximum recursion depth exceeded in comparison. Is this just a stack overflow? Is there a way to get around it?

Answer 1

It is a guard against a stack overflow, yes. Python (or rather, the CPython implementation) doesn't optimize tail recursion, and unbridled recursion causes stack overflows. You can check the recursion limit with sys.getrecursionlimit:

import sys print(sys.getrecursionlimit()) 

and change the recursion limit with sys.setrecursionlimit:

sys.setrecursionlimit(1500) 

but doing so is dangerous -- the standard limit is a little conservative, but Python stackframes can be quite big.

Python isn't a functional language and tail recursion is not a particularly efficient technique. Rewriting the algorithm iteratively, if possible, is generally a better idea.

Answer 2

Looks like you just need to set a higher recursion depth:

import sys sys.setrecursionlimit(1500)