问题
I'm receiving this error in my Django application, however, it only happens once a day or less and it's proving extremely difficult to debug.
Environment:
Request Method: POST
Django Version: 1.3.1
Python Version: 2.6.6
Installed Applications:
['django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'fimedlabs',
'data',
'djcelery']
Installed Middleware:
('django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'fimedlabs.auth.userMiddleWare')
Traceback:
File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py" in get_response
178. response = middleware_method(request, response)
File "/usr/local/lib/python2.6/dist-packages/django/contrib/sessions/middleware.py" in process_response
36. request.session.save()
File "/usr/local/lib/python2.6/dist-packages/django/contrib/sessions/backends/db.py" in save
57. session_data = self.encode(self._get_session(no_load=must_create)),
File "/usr/local/lib/python2.6/dist-packages/django/contrib/sessions/backends/base.py" in encode
93. pickled = pickle.dumps(session_dict, pickle.HIGHEST_PROTOCOL)
Exception Type: PicklingError at /
Exception Value: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed
I've tried the answer to this:
How to tell for which object attribute pickle fails?
by adding self to the actual error to see if that would print anything in the Django error to no avail.
Where can I print out the object that is giving issues from this error so that it will appear in the Django error page?
Thanks! ~Matt
EDIT: The only object I'm storing in the cache, is a user object with the code:
class user(object):
username = str()
userid = uuid.UUID(int=0)
client = models.Client()
clientid = uuid.UUID(int=0)
clientname = ''
data = models.User()
accesslevel = models.AccessLevel()
active = False
client_active = False
isFimed = False
isFimedAdmin = False
isClientAdmin = False
isFimedManager = False
mysettingsform = None
viewingas = False
menu = []
_exists = False
_authenticated = False
def __str__(self):
return str(self.__dict__.copy())
def __getstate__(self):
return self.__dict__.copy()
def __setstate__(self, dict):
self.__dict__ = dict
def __init__(self, username=None):
if username:
self.initialize(username)
def initialize(self, username):
self.username = username
model = models.User.objects.filter(username=username).all()
if len(model) == 1:
model = model[0]
self.data = model
self._exists = True
self.userid = self.data.id
self.active = self.data.active
self.isFimed = self.data.isFimed()
self.isFimedAdmin = self.data.isFimedAdmin()
self.isClientAdmin = self.data.isClientAdmin()
self.isFimedManager = self.data.isFimedManager()
self.mysettingsform = UserFormSelf(initial={"id":model.id, "username":model.username, "name":model.name, "email":model.email, "phone":model.phone})
self.accesslevel = models.AccessLevel.objects.filter(id=self.data.accesslevel_id)[:1][0].level
cli = self.data.client
self.client = cli
self.clientid = cli.id
self.clientname = cli.name
if cli.active:
self.client_active = True
model.lastlogin = datetime.datetime.now()
model.save()
self.menu = getMenu(self.data)
else:
self._exists = False
def authenticate(self, password):
self._authenticated = False
if (self.active == False or self.client_active == False):
return False
if self._exists:
import hashlib
hash = hashlib.md5('%s%s' % (str(password), self.data.pwsalt)).hexdigest()
if hash == self.data.pwhash:
self._authenticated = True
return True
return False
def updateUser(self):
self.initialize(models.User.objects.filter(id=self.userid).get().username)
def mkContext(self):
c = Context()
c['menu'] = self.menu
c['user'] = self
c['language'] = language
c['colors'] = colors
c["isFimed"] = self.isFimed
c["isFimedAdmin"] = self.isFimedAdmin
c["isClientAdmin"] = self.isClientAdmin
c["isFimedManager"] = self.isFimedManager
c["mysettingsform"] = self.mysettingsform
return c
EDIT: WSGI file after Werkzeug:
import django.core.handlers.wsgi
djangoapplication = django.core.handlers.wsgi.WSGIHandler()
def application(environ, start_response):
if 'SCRIPT_NAME' in environ:
del environ['SCRIPT_NAME']
return djangoapplication(environ, start_response)
# The following lines enable the werkzeug debugger
import django.views.debug
def null_technical_500_response(request, exc_type, exc_value, tb):
raise exc_type, exc_value, tb
django.views.debug.technical_500_response = null_technical_500_response
from werkzeug.debug import DebuggedApplication
application = DebuggedApplication(application, evalex=True)
回答1:
Where can I print out the object that is giving issues from this error so that it will appear in the Django error page?
The short answer - without recompiling cPickle, you can't.
Longer answer: This is the piece of code that raises the exception:
root $ grep -Hra "attribute lookup" /usr/lib64/ 2>/dev/null | grep -a failed
/usr/lib64/python2.7/lib-dynload/cPickle.so:H�H���P0H�5zM H�=1��M��H��H�ZM �����H�=�1�H���M��H��H��M �����H�4M H�5~H���H���������H�M H�5tH���H���������H��L H�5�H���qH�����d���H�M H�5NH���SH�����F���H�dM H�5bH���5H�����(���H�=X1��O��H�HC H�5I H�=U1�A��H��L �vH��H��I�������H���RK��H�=.H����J��H�5$H��H��H�D$�G��H�D$H��tH�H��H��H��gH�DL�ttH�qH�5nH�=kH��1��XK��H�5bH��H��I����F��H�5\L��H���F��H��tH�EH��H��H�E��M�������I�$H��H��I�$�t���I�DL���P0�d���f�H�EH��H��H�E�F���H�H���P0�7���@H�|$H��P0�����H�H���P0�����H�H���P0�k�����UH��SH�H�H: H���tH�;: H���H�H���u�H�[��H��M��H��attribute deletion is not supportedunsupported pickle protocol: %dargument must have 'read' and 'readline' attributespickle protocol %d asked for; the highest available protocol is %dargument must have 'write' attributeGlobal and instance pickles are not supported.Attempt to getvalue() a non-list-based picklerUnexpected data in internal listBINSTRING pickle has negative byte countno int where int expected in memoCan't pickle %s: import of module %s failedCan't pickle %s: attribute lookup %s.%s failedCan't pickle %s: it's not the same object as %s.%sCan't pickle %s: extension code %s isn't an integerCan't pickle %s: extension code %ld is out of rangecould not convert string to intLONG pickle has negative byte countcould not convert string to floatBINUNICODE pickle has negative byte countunregistered extension code %ld_inverted_registry[%ld] isn't a 2-tuple of stringsA load persistent id instruction was encountered,
If you look close enough, there's a piece that says
Can't pickle %s: attribute lookup %s.%s failed
Now, if you download Python sources, you can easily find the piece of code responsible for raising the exception in the function static int save_global(Picklerobject *self, PyObject *args, PyObject *name) of ./Modules/cPickle.c:
klass = PyObject_GetAttrString(mod, name_str);
if (klass == NULL) {
cPickle_ErrFormat(PicklingError,
"Can't pickle %s: attribute lookup %s.%s "
"failed",
"OSS", args, module, global_name);
goto finally;
}
So, the best you can do to debug this error is to format the string differently (probably providing PyString_AS_STRING((PyStringObject *)name), recompile and install the modified version of Python.
Yeah, I know that's too bad. I just had the same problem myself.
回答2:
In my case (not Django related) this exception was thrown by multiprocessing.Pool.map when a lambda was passed as the target function. Creating a named function and passing the needed context data structures via the initargs parameter (rather than via the closure) solved the issue.
To summarize, the bad use-case that triggered the exception was:
import multiprocessing as mp
context = some_object
pool = mp.Pool()
worker_func = lambda x: work(x, context)
results = pool.map(worker_func, data_list)
回答3:
Use something like django-extensions to install the werkzeug debugger. You will be able to interact with each stackframe. At that point, you can try pickling all of the keys and values in the session dict.
回答4:
If you are storing a user object, you may be affected by this bug: https://code.djangoproject.com/ticket/16563
That said, your best bet is going to be to just modify the Django source code at line 93 of /usr/local/lib/python2.6/dist-packages/django/contrib/sessions/backends/base.py where your exception occurs.
Just log session_dict. In most cases it will be really obvious what is wrong. (Indeed, if your traceback shows Local Vars, you already have this)
来源：https://stackoverflow.com/questions/10898268/cant-pickle-type-function-attribute-lookup-builtin-function-failed