Wednesday, 15 May 2013

Re: Mysterious Python pyc file corruption problems

Am 16.05.2013 01:29, schrieb Brian Murray:
> On Wed, May 15, 2013 at 03:15:05PM -0700, Brian Murray wrote:
>> On Wed, May 15, 2013 at 04:36:56PM -0400, Barry Warsaw wrote:
>>> Hello Developers,
>>>
>>> I am trying to debug and fix a particularly vexing problem in Python
>>> that manifests on Ubuntu in several different ways. I have a
>>> hypothesis about the problem, but there are still some mysteries and I
>>> don't know how to reproduce it. I think I can fix it, but I'm sending
>>> this message (and soon, another one to python-dev with more technical
>>> details) in the hopes that you might have other ideas about how it can
>>> happen, or have a reliable way to reproduce the bug.
>>>
>>> The problem can show up in any package, but Brian has started to
>>> collect a number of bugs that all seem to be related (and I think Steve
>>> is going to open a megabug to dupe them all to). The common way this
>>> manifests is a traceback on an import statement. The actual error can
>>> be a "ValueError: bad marshal data (unknown type code)" such as in LP:
>>> #1010077, or an "EOFError: EOF read where not expected" as in LP:
>>> #1060842. We have many more instances of both of these.
>>>
>>> Both of these exceptions come from Python's marshal code (marshal.c).
>>> marshal is the low-level serialization protocol used to cache Python
>>> byte code into .pyc files, so both of these exception imply corrupt
>>> .pyc files, and in fact, the workaround is always to essentially blow
>>> away the .pyc file and re-create it. (Various different techniques can
>>> be used, but they all boil down to the same thing.)
>>>
>>> Another commonality is that this bug -- so far -- has not been observed
>>> in any Python 3.3 code, only 3.2 and earlier, including 2.7 and 2.6.
>>
>> I've found one bug where the interpreter is python3.3:
>>
>> http://launchpad.net/bugs/1178599
>>
>> This looks to be a fresh install of Raring so the apport data seems
>> trustworthy. (There are some apport issues with delayed reporting and
>> distribution upgrades.) I'll be doing a full search of Launchpad bugs
>> shortly.
>
> And http://launchpad.net/bugs/1107175
>
> That's all the bugs tagged apport-crash and raring with python3.3 in
> InterpreterPath and EOFError or bad marshal data in the apport generated
> Title.
>
> Looking both of these up at errors.ubuntu.com using the bug parameter
> (yeah!) I only found one example which appears to be the same report as in
> bug 1178599.

would it be possible to find out for each bug report which file seems to be
corrupt, and which package it belongs too? To see if this breakage is limited
to certain packages. So far for the two bugs mentioned it's python3.3-minimal,
and python3-apport.



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