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#! /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.
"""
import sys
import itertools
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 test_cpickle(_cache={}):
import io
try:
import _pickle
except ImportError:
print("cannot import _pickle, skipped!")
return
l = None
for n in itertools.count():
try:
l = _cache[n]
continue # Already tried and it works, let's save some time
except KeyError:
for i in range(100):
l = [l]
_pickle.Pickler(io.BytesIO(), protocol=-1).dump(l)
_cache[n] = l
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")
check_limit(limit, "test_cpickle")
print("Limit of %d is fine" % limit)
limit = limit + 100
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