Bugs item #780714, was opened at 2003-07-31 01:37
Message generated for change (Comment added) made by josiahcarlson
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Category: Python Interpreter Core
Group: Python 2.3
Status: Closed
Resolution: Fixed
Priority: 5
Submitted By: Stefan Gregory (stefan_gregory)
Assigned to: Nobody/Anonymous (nobody)
Summary: infinite __str__ recursion in thread causes seg fault
Initial Comment:
The following code reliably produces a segmentation
fault under Solaris8 in Python2.3, Python2.2,
Python2.1.3 and Python1.5. It produces a Bus Error when
run on Python2.2 under OSX. Clearly it should produce a
Python RuntimeError.
import thread, time
class Frog:
def __str__(self):
return str(self)
f = Frog()
thread.start_new_thread(str,(f,))
time.sleep(1000)
This problem manifests in scenarios such as when you
have 2 publishing objects (such as HTMLgen objects) A
and B and you put A inside B and B inside A and each
objects __str__ method calls its childrens __str__
methods and voila! (I hope this might be the reason my
Zope server has been intermitently crashing for the
past year or so though I have not found any recursive
structures yet.)
With Python2.3 gdb reports:
vgetargskeywords (args=0x1bdaf0, keywords=0x0,
format=0xd2579 "0:str", kwlist=0xf7b4c,
p_va=0xfed0C02c) at Python/getargs.c:1167
Though with Python2.1 it dies at line 330 in getargs.c.
----------------------------------------------------------------------
Comment By: Josiah Carlson (josiahcarlson)
Date: 2006-08-16 00:42
Message:
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>>> import sys
>>> sys.setrecursionlimit(10000)
>>> class foo:
... def __str__(self):
... return str(self)
...
>>> import threading
>>> threading.Thread(target=foo().__str__).start()
Kills 2.3, 2.4, and 2.5 on Windows, and 2.3 and 2.4 on linux
(I can't test 2.5 on linux). Running in the main thread on
Windows doesn't seem to be a big deal:
>>> import sys
>>> sys.setrecursionlimit(10000)
>>> class foo:
... def __str__(self):
... return str(self)
...
>>> try:
... str(foo())
... except Exception, why:
... print why
...
Stack overflow
>>>
Note that the above crashes 2.3 and 2.4 on Linux.
This is still a bug, at least in maintenance on 2.4.
Suggested reopen.
----------------------------------------------------------------------
Comment By: SourceForge Robot (sf-robot)
Date: 2006-08-13 19:20
Message:
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This Tracker item was closed automatically by the system. It was
previously set to a Pending status, and the original submitter
did not respond within 14 days (the time period specified by
the administrator of this Tracker).
----------------------------------------------------------------------
Comment By: Georg Brandl (gbrandl)
Date: 2006-07-30 04:16
Message:
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Under 2.5, I get a runtime error now, so this might be fixed.
----------------------------------------------------------------------
Comment By: Brett Cannon (bcannon)
Date: 2003-08-05 12:22
Message:
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Forgot to mention that Modules/threadmodule.c has
thread_PyThread_start_new_thread which uses Python/
thread_*.h's PyThread_start_new_thread for executing threads;
the '*' is replaced with the threading library used on your
platform. OS X should use thread_pthread.h (I think).
----------------------------------------------------------------------
Comment By: Brett Cannon (bcannon)
Date: 2003-08-05 12:19
Message:
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If you run ``str(Frog())`` instead of a bunch of threads you do get
a RuntimeError. Looks like this bus error has something to do
with thread.start_new_thread and not 'str'. It might be that since
it runs using pthreads it does not have the built-in recursion limit
check that the Python interpreter has. Anyone with more
experience with the 'thread' module have any ideas?
----------------------------------------------------------------------
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=780714&group_id=5470
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