ref: 12fa017f3fc2687d3afb166fd30d9b134abb1da5
dir: /sys/src/cmd/python/Misc/find_recursionlimit.py/
#! /usr/bin/env python
"""Find the maximum recursion limit that prevents core dumps
This script finds the maximum safe recursion limit on a particular
platform. If you need to change the recursion limit on your system,
this script will tell you a safe upper bound. To use the new limit,
call sys.setrecursionlimit.
This module implements several ways to create infinite recursion in
Python. Different implementations end up pushing different numbers of
C stack frames, depending on how many calls through Python's abstract
C API occur.
After each round of tests, it prints a message
Limit of NNNN is fine.
It ends when Python causes a segmentation fault because the limit is
too high. On platforms like Mac and Windows, it should exit with a
MemoryError.
NB: A program that does not use __methods__ can set a higher limit.
"""
import sys
class RecursiveBlowup1:
def __init__(self):
self.__init__()
def test_init():
return RecursiveBlowup1()
class RecursiveBlowup2:
def __repr__(self):
return repr(self)
def test_repr():
return repr(RecursiveBlowup2())
class RecursiveBlowup4:
def __add__(self, x):
return x + self
def test_add():
return RecursiveBlowup4() + RecursiveBlowup4()
class RecursiveBlowup5:
def __getattr__(self, attr):
return getattr(self, attr)
def test_getattr():
return RecursiveBlowup5().attr
class RecursiveBlowup6:
def __getitem__(self, item):
return self[item - 2] + self[item - 1]
def test_getitem():
return RecursiveBlowup6()[5]
def test_recurse():
return test_recurse()
def check_limit(n, test_func_name):
sys.setrecursionlimit(n)
if test_func_name.startswith("test_"):
print test_func_name[5:]
else:
print test_func_name
test_func = globals()[test_func_name]
try:
test_func()
except RuntimeError:
pass
else:
print "Yikes!"
limit = 1000
while 1:
check_limit(limit, "test_recurse")
check_limit(limit, "test_add")
check_limit(limit, "test_repr")
check_limit(limit, "test_init")
check_limit(limit, "test_getattr")
check_limit(limit, "test_getitem")
print "Limit of %d is fine" % limit
limit = limit + 100