[Python-Dev] Mysterious Python pyc file corruption problems

[Nick Coghlan]

On Sat, May 18, 2013 at 3:19 AM, David Malcolm <dmalcolm at redhat.com> wrote:
> On Fri, 2013-05-17 at 12:42 -0400, Barry Warsaw wrote:
>> On May 16, 2013, at 04:52 PM, Terry Jan Reedy wrote:
>>
>> >If the corruption only happens on Ubuntu, that would constitute 'rhyme'
>> >;-). I realize that asking for reports on other systems is part of the reason
>> >you posted, but I don't remember seeing any others yet.
>>
>> Right. :)  It's harder to dig out similar problems in Debian[1] but it's
>> pretty clear that there have been *some* similar reports in Debian.  Ubuntu
>> and Debian share almost all their Python infrastructure.  It would definitely
>> be interesting to whether Fedora/RedHat or any other Linux distros have seen
>> similar problems.
>
> FWIW I don't recall seeing such problems on Fedora/RH, though that could
> be due to...
>
>> I don't know how Fedora/RH does package installation.  In Debian/Ubuntu, we do
>> not ship pyc files, but instead they are generated in "post-installation"
>> scripts, which boil down to calls to `$PYTHON -m py_compile - < filenames`.
>
> Fedora/RH pregenerate the .pyc files during rpm creation, and they exist
> as part of the rpm payload.

So in effect, we'd always be doing an atomic rename (and file
conflicts between RPMs wouldn't be allowed in the first place).

Combined with Brett's info that even 3.3 doesn't use atomic renames
for pre-compilation (only for implicit compilation), I consider that
strong evidence in favour of Guido's theory that Debian are getting
write conflicts somewhere.

Cheers,
Nick.

--
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia