Bugs item #742342, was opened at 2003-05-23 10:03 Message generated for change (Comment added) made by collinwinter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=742342&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Interpreter Core >Group: Python 2.6 >Status: Closed >Resolution: Fixed Priority: 5 Private: No Submitted By: Christian Eder (chris_ce) Assigned to: Nobody/Anonymous (nobody) Summary: Python crashes if recursively reloading modules Initial Comment: If one tries to recursively reload modules, python crashes with a segfault. e.g. if the file "foo.py" looks something like: import foo reload (foo) .... the python interpreter crashes when reading this file. I have been able to reproduce the problem both with python2.2 and python2.3 under linux. Although recursive reloads are faulty code, this should lead to an exception but not to a segfault of the interpreter. In our case, this bug allows a faulty user script to crash our program. Sorry if this is already a known bug, but I searched in Sorceforge (and also in Google) and did not find something similar. ---------------------------------------------------------------------- >Comment By: Collin Winter (collinwinter) Date: 2007-03-12 12:51 Message: Logged In: YES user_id=1344176 Originator: NO Fixed in r54291 (trunk), r54294 (release25-maint). Thanks for the bug report, Christian! ---------------------------------------------------------------------- Comment By: Christian Eder (chris_ce) Date: 2003-05-24 05:10 Message: Logged In: YES user_id=785436 You're right, there's nothing wrong with recursive imports (we also use them in our sources), but with recursive reloads. As far as I know the import statement reads the module only if it is not registered in sys.modules. If modules are added to sys.modules before they are parsed (as I suppose they are) a recursive import does no harm because the module is read only once. But I think the reload statement re-reads the file unconditionally (is it so ?) and may therefore cause an endless recursion. If the interpreter keeps a graph of files and the relations which file causes a reading of another file (either by importing a file which is not yet in sys.modules or by reloading), situations like recursive reloads could be easily detected as they would introduce cycles to the graph. However this is just an idea, maybe an implementation would cost too much permance. I will research the problem further and notice you if I find some kind of workaround. ---------------------------------------------------------------------- Comment By: Tim Peters (tim_one) Date: 2003-05-23 14:56 Message: Logged In: YES user_id=31435 The default recursion limit is unconditionally defined -- it doesn't vary across platforms. If you can submit a patch, that would help. Note that there's nothing wrong with (indirectly) recursive imports in Python (they're delicate but frequently used anyway), so we can't raise an exception on that. ---------------------------------------------------------------------- Comment By: Christian Eder (chris_ce) Date: 2003-05-23 14:30 Message: Logged In: YES user_id=785436 I tried it on 2 of our development PC's and got the following results on both of them: sys.getrecursionlimit () ===> 1000 python find_recursionlimit.py ===> 2800 Seems a bit strange, doesn't it ? I had expected the sys.recursionlimit to be higher than the actual limit. Anyway, recursive reloads are quite easy to detect, so shouldn't the interpreter detect such statements and raise an appropriate error exception (not resulting in a maximum recursion depth exceeded error) ---------------------------------------------------------------------- Comment By: Jeremy Hylton (jhylton) Date: 2003-05-23 12:01 Message: Logged In: YES user_id=31392 I expect this is a platform-specific problem with the Python recursion limit. Can you report two things? The value returned by sys.getrecursionlimit(), and the last limit reported by Misc/find_recursionlimit.py. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=742342&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
