Windows debugging symbols for python 2.5.4 and pywin32 214

Alexandre Fayolle alexandre.fayolle at logilab.fr
Fri Apr 23 13:59:55 CEST 2010


On Friday 23 April 2010 08:36:01 Mark Hammond wrote:
> On 22/04/2010 7:23 AM, Alexandre Fayolle wrote:
> > Hi everyone,
> >
> > I have a production server running a Windows Service written in Python,
> > which uses python 2.5.4 (yes I know it is old, but I am somewhat stuck
> > with this for now) and pywin32 214.
> >
> > Given a set of manipulations, I get a stack overflow in the service, and
> > a bad crash. The same operation when running without
> > win32serviceutil.ServiceFramework does not trigger the bug. I'm looking
> > for some debugging tools (debug build of the interpreter and the pywin32
> > libraries) that some good soul could have kept from a previous debugging
> > session to try to get a C stack trace and understand what causes this.
> 
> I expect the problem might be that pythonservice.exe isn't linked with a
> large enough stack - python itself builds with a larger than default
> stack.  That difference could cause a recursive function to hard-crash
> before Python itself detected the recursion as being too deep.
> 
> You could test this by playing with the sys.setrecursionlimit function -
> at some limit I expect you would find the hard-crash would be replaced
> with a max recursion exception.  Let me know if that is the case and
> I'll be sure to adjust the stack size for the next pywin32 build.
> 
> > Any hint towards what could cause that stack overflow would be welcome
> > too. The application is multithreaded (and uses pyro and twisted). I can
> > provide more information for the curious.
> 
> Some parts of twisted are written such that server responses are
> processed recursively, and very large input can cause the recursion
> limit to be hit.  I'm still occasionally bitten by this in the IMAP
> client code...

Thank you for this very helpful information. I've found on my side that 
upgrading to python2.6 will prevent the crash from happening in the reported 
conditions, and used this as a fix (currently running extensive tests to be on 
the safe side). 

Runnning 2.6 will among other things enable me to use a recent VS compiler to 
rebuild stuff if required. 

I'm very interested in a pywin32 build with a larger stack for 
pythonservice.exe, as this would seriously increase my confidence level and 
improve my sleep quality :-) 

-- 
Alexandre Fayolle                              LOGILAB, Paris (France)
Formations Python, CubicWeb, Debian :  http://www.logilab.fr/formations
Développement logiciel sur mesure :      http://www.logilab.fr/services
Informatique scientifique:               http://www.logilab.fr/science



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