[New-bugs-announce] [issue14474] mishandling of AttributeError in threads

Pierre Ossman report at bugs.python.org
Mon Apr 2 14:08:20 CEST 2012

New submission from Pierre Ossman <ossman at cendio.se>:

These three things do not mix:

 - AttributeError
 - Threads
 - Object methods

An unhandled AttributeError thrown in a thread will not call sys.excepthook if the thread's start function is a class/object method.

Test case:

import sys
import thread

class Dummy:
	def worker(self):
		raise AttributeError

thread.start_new_thread(Dummy().worker, ())


Note that you do not get a traceback here. Throwing any other exception type works fine, as does having worker() be a simple function.

I think I've traced the issue to Objects/classobject.c:instance_repr(). It tries to look up the method, making sure to handle any AttributeError this might cause. But it fails to save and restore and Exception currently already active, effectively clearing out the current exception.

components: Interpreter Core
messages: 157350
nosy: ossman
priority: normal
severity: normal
status: open
title: mishandling of AttributeError in threads
versions: Python 2.7

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