[Python-checkins] r66457 - in python/trunk/Misc: NEWS find_recursionlimit.py
antoine.pitrou
python-checkins at python.org
Sat Sep 13 22:30:30 CEST 2008
Author: antoine.pitrou
Date: Sat Sep 13 22:30:30 2008
New Revision: 66457
Log:
Issue #3850: Misc/find_recursionlimit.py was broken.
Reviewed by A.M. Kuchling.
Modified:
python/trunk/Misc/NEWS
python/trunk/Misc/find_recursionlimit.py
Modified: python/trunk/Misc/NEWS
==============================================================================
--- python/trunk/Misc/NEWS (original)
+++ python/trunk/Misc/NEWS Sat Sep 13 22:30:30 2008
@@ -15,6 +15,14 @@
Library
-------
+Tools/Demos
+-----------
+
+- Issue #3850: recursion tests in Misc/find_recursion_limit.py can raise
+ AttributeError instead of RuntimeError, depending in which C API call
+ exactly the recursion limit is exceeded. Consequently, both exception types
+ are caught and silenced.
+
What's New in Python 2.6 release candidate 1?
=============================================
Modified: python/trunk/Misc/find_recursionlimit.py
==============================================================================
--- python/trunk/Misc/find_recursionlimit.py (original)
+++ python/trunk/Misc/find_recursionlimit.py Sat Sep 13 22:30:30 2008
@@ -1,22 +1,30 @@
#! /usr/bin/env python
-"""Find the maximum recursion limit that prevents core dumps
+"""Find the maximum recursion limit that prevents interpreter termination.
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.
+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.
+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.
+The highest printed value of "NNNN" is therefore the highest potentially
+safe limit for your system (which depends on the OS, architecture, but also
+the compilation flags). Please note that it is practically impossible to
+test all possible recursion paths in the interpreter, so the results of
+this test should not be trusted blindly -- although they give a good hint
+of which values are reasonable.
+
+NOTE: When the C stack space allocated by your system is exceeded due
+to excessive recursion, exact behaviour depends on the platform, although
+the interpreter will always fail in a likely brutal way: either a
+segmentation fault, a MemoryError, or just a silent abort.
NB: A program that does not use __methods__ can set a higher limit.
"""
@@ -88,7 +96,10 @@
test_func = globals()[test_func_name]
try:
test_func()
- except RuntimeError:
+ # AttributeError can be raised because of the way e.g. PyDict_GetItem()
+ # silences all exceptions and returns NULL, which is usually interpreted
+ # as "missing attribute".
+ except (RuntimeError, AttributeError):
pass
else:
print "Yikes!"
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