v5.0.0/Mac Crash on db connection close

[Fabien Lydoire @ Taktik]

I'm running the server on Mac OS X Leopard 10.5.6, using python 2.5 provided by the system and a few other modules I compiled myself.

Trying to connect to the data base raises the following error

INFO:web-services:the server is running, waiting for connections...
INFO:dbpool:Connecting to template1
INFO:dbpool:Closing all connections to template1
Closing connection <connection>
Bus error

I tried with previous versions and it works with v5 RC1 which still used psycopg (1).
With RC2, psycopg2 has been used and the code of sql_db.py has been changed too.

Debugging, it seems that the "wrapper" method from sql_db.py is called over and over, leading to a stack overflow and an app crash.

  def check(f):
        from tools.func import wraps

        @wraps(f)
        def wrapper(self, *args, **kwargs):
            if not hasattr(self, '_obj'):
                raise psycopg2.ProgrammingError('Unable to use the cursor after having closing it')
            return f(self, *args, **kwargs)
        return wrapper

[Fabien Lydoire @ Taktik (fl-taktik)]

I just patched sql_db.py.
I know it's an horrible fix, it raises exceptions, but it breaks the infinite loop.
I hope that will help the OpenERP Team to make a better fix.

         @wraps(f)
         def wrapper(self, *args, **kwargs):
- if not hasattr(self, '_obj'):
+ if not (f.func_name=='__getattr__' and args==('_obj',)) and not hasattr(self, '_obj'):
                 raise psycopg2.ProgrammingError('Unable to use the cursor after having closing it')
             return f(self, *args, **kwargs)
         return wrapper

     @check
     def __getattr__(self, name):
- return getattr(self._obj, name)
+ if name!='_obj':
+ return getattr(self._obj, name)
+ else:
+ return None

[mark.a.m (mark-a-m)]

The problem here is, given the case that some callee (e.g. __del__) wants to see if aCursor contains an attribute named '_obj' hasattr calls getattr to see if it raises an exception, getattr in turn calls __getattr__ which is wrapped in checks wrapper method which uses hasattr triggering an infinite recursion.

--- sql_db.py.bak 2009-03-05 22:59:42.000000000 +0100
+++ sql_db.py 2009-03-06 00:12:34.000000000 +0100
@@ -181,9 +181,11 @@
     def rollback(self):
         return self._cnx.rollback()

- @check
     def __getattr__(self, name):
- return getattr(self._obj, name)
+ if name =='_obj':
+ raise AttributeError("No attribute named _obj")
+ else:
+ return getattr(self._obj, name)

 class ConnectionPool(object):
     def __init__(self, pool, dbname):

[mark.a.m (mark-a-m)]

Bug has been confirmed for mac and freebsd, please see the attached patch for a fix and explanation.

[Fabien Lydoire @ Taktik (fl-taktik)]

I confirm the patch solved the problem on Mac OS X. Thanks !

[Santi Argüeso(Pexego) (santiago-pexego)]

I've tested the patch on a FreeBSD 7_STABLE server running 5.0.0-3 and now it works.

thank you!

[mark.a.m (mark-a-m)]

Christophe (OpenERP) wrote:
> ** Changed in: openobject-server/trunk
> Assignee: Fabien (Open ERP) (fp-tinyerp) => Christophe (OpenERP) (kangol)

If you need additional information about the bug I'd be glad to help. It
should be quite clear that '@check' triggers a potential infinite recursion.

Regards, Mark

[Christophe Simonis (OpenERP) (kangol)]

On 03.04.2009 19:13, mark.a.m wrote:
> Christophe (OpenERP) wrote:
>> ** Changed in: openobject-server/trunk
>> Assignee: Fabien (Open ERP) (fp-tinyerp) => Christophe (OpenERP) (kangol)
>
> If you need additional information about the bug I'd be glad to help. It
> should be quite clear that '@check' triggers a potential infinite recursion.
>
> Regards, Mark
>
Not anymore.

--
Christophe Simonis
Developer
OpenERP - Tiny sprl
Chaussée de Namur, 40
B-1367 Gérompont
Tel: [phone]
Web: http://openerp.com
Blog: http://christophe-simonis-at-tiny.blogspot.com

TinyERP: making ERP Tiny and Easy To use
   -- Sidahmed Dine, 2006

[Olivier Dony (Odoo) (odo-openerp)]

updating status.. all 5.0 fixes have been ported to 6.0 a while ago