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54ac832a24
This patch changes a few of the scripts to have __name__=='__main__' clauses so that they are importable without running. Also fixes the syntax errors revealed by the tests.
122 lines
3.5 KiB
Python
Executable File
122 lines
3.5 KiB
Python
Executable File
#! /usr/bin/env python3
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"""Find the maximum recursion limit that prevents interpreter termination.
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This script finds the maximum safe recursion limit on a particular
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platform. If you need to change the recursion limit on your system,
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this script will tell you a safe upper bound. To use the new limit,
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call sys.setrecursionlimit().
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This module implements several ways to create infinite recursion in
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Python. Different implementations end up pushing different numbers of
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C stack frames, depending on how many calls through Python's abstract
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C API occur.
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After each round of tests, it prints a message:
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"Limit of NNNN is fine".
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The highest printed value of "NNNN" is therefore the highest potentially
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safe limit for your system (which depends on the OS, architecture, but also
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the compilation flags). Please note that it is practically impossible to
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test all possible recursion paths in the interpreter, so the results of
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this test should not be trusted blindly -- although they give a good hint
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of which values are reasonable.
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NOTE: When the C stack space allocated by your system is exceeded due
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to excessive recursion, exact behaviour depends on the platform, although
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the interpreter will always fail in a likely brutal way: either a
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segmentation fault, a MemoryError, or just a silent abort.
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NB: A program that does not use __methods__ can set a higher limit.
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"""
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import sys
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import itertools
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class RecursiveBlowup1:
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def __init__(self):
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self.__init__()
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def test_init():
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return RecursiveBlowup1()
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class RecursiveBlowup2:
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def __repr__(self):
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return repr(self)
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def test_repr():
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return repr(RecursiveBlowup2())
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class RecursiveBlowup4:
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def __add__(self, x):
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return x + self
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def test_add():
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return RecursiveBlowup4() + RecursiveBlowup4()
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class RecursiveBlowup5:
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def __getattr__(self, attr):
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return getattr(self, attr)
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def test_getattr():
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return RecursiveBlowup5().attr
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class RecursiveBlowup6:
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def __getitem__(self, item):
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return self[item - 2] + self[item - 1]
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def test_getitem():
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return RecursiveBlowup6()[5]
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def test_recurse():
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return test_recurse()
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def test_cpickle(_cache={}):
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import io
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try:
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import _pickle
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except ImportError:
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print("cannot import _pickle, skipped!")
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return
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k, l = None, None
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for n in itertools.count():
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try:
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l = _cache[n]
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continue # Already tried and it works, let's save some time
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except KeyError:
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for i in range(100):
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l = [k, l]
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k = {i: l}
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_pickle.Pickler(io.BytesIO(), protocol=-1).dump(l)
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_cache[n] = l
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def check_limit(n, test_func_name):
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sys.setrecursionlimit(n)
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if test_func_name.startswith("test_"):
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print(test_func_name[5:])
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else:
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print(test_func_name)
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test_func = globals()[test_func_name]
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try:
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test_func()
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# AttributeError can be raised because of the way e.g. PyDict_GetItem()
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# silences all exceptions and returns NULL, which is usually interpreted
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# as "missing attribute".
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except (RuntimeError, AttributeError):
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pass
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else:
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print("Yikes!")
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if __name__ == '__main__':
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limit = 1000
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while 1:
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check_limit(limit, "test_recurse")
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check_limit(limit, "test_add")
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check_limit(limit, "test_repr")
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check_limit(limit, "test_init")
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check_limit(limit, "test_getattr")
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check_limit(limit, "test_getitem")
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check_limit(limit, "test_cpickle")
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print("Limit of %d is fine" % limit)
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limit = limit + 100
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