我在Django应用程序中收到此错误，但是，它每天只发生一次或更少，并且证明调试非常困难。
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
我已经尝试过这个答案了：
How to tell for which object attribute pickle fails?
通过将self添加到实际错误中来查看是否会在Django错误中打印任何内容都无济于事。
在哪里可以打印出来自此错误的问题的对象，以便它出现在Django错误页面中？
谢谢！ 马特〜
编辑：我存储在缓存中的唯一对象是一个用户对象，代码为：
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
编辑：Werkzeug之后的WSGI文件：
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)
答案 0 :(得分：9)
在我的情况下（不是Django相关）当lambda作为目标函数传递时，multiprocessing.Pool.map抛出了这个异常。创建一个命名函数并通过initargs参数（而不是通过闭包）传递所需的上下文数据结构解决了这个问题。
总结一下，触发异常的坏用例是：
import multiprocessing as mp
context = some_object
pool = mp.Pool()
worker_func = lambda x: work(x, context)
results = pool.map(worker_func, data_list)
答案 1 :(得分：6)
在哪里可以打印出来自此错误的问题的对象，以便它出现在Django错误页面中？
简短的回答 - 没有重新编译cPickle，你就不能。
更长的回答：这是引发异常的代码段：
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,
如果你看得足够近，那就是
Can't pickle %s: attribute lookup %s.%s failed
现在，如果您下载Python源代码，您可以轻松找到负责在static int save_global(Picklerobject *self, PyObject *args, PyObject *name)的函数./Modules/cPickle.c中引发异常的代码段：
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;
}
因此，调试此错误的最佳方法是以不同方式格式化字符串（可能提供PyString_AS_STRING((PyStringObject *)name)，重新编译并安装修改后的Python版本。
答案 2 :(得分：1)
使用django-extensions之类的东西来安装werkzeug调试器。您将能够与每个堆栈帧进行交互。此时，您可以尝试在会话字典中挑选所有键和值。
答案 3 :(得分：1)
如果您要存储用户对象，则可能会受到此错误的影响： https://code.djangoproject.com/ticket/16563
那就是说，你最好的选择就是在/usr/local/lib/python2.6/dist-packages/django/contrib/sessions/backends/base.py第93行修改Django源代码。发生异常的地方。
只需记录session_dict。在大多数情况下，真正明显的是什么是错的。 （事实上，如果你的追溯显示本地变种，你已经有了这个）