NotImplementedError for cache clear

Gwildor commented 10 years ago

I'm familiar with ticket #439, and I'm running DDT 1.0.1, which includes the fix created for that ticket. However, when I try to clear the cache with DDT enabled, I get a NotImplementedError, which originates directly from the django.core.cache.backends.base.BaseCache.clear method. As my backend, I'm running memcached. Disabling the DDT works; no exception is raised. Note that I'm trying to clear the cache from a signal receiver (not sure if that's relevant, so just throwing it out there).

When I do from django.core.cache import cache; print cache I get <CacheStatTracker for <django.core.cache.backends.memcached.MemcachedCache object at 0x106b7a290>>.

aaugustin commented 10 years ago

Can you provide the full stack trace please?

Gwildor commented 10 years ago

Here you go:

Django Version: 1.6.2
Python Version: 2.7.5
Installed Applications:
('nested_inlines',
 'django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.sites',
 'django.contrib.humanize',
 'ckeditor',
 'sorl.thumbnail',
 'south',
 'djcelery',
 'storages',
 'forms_builder.forms',
 'post_office',
 'feincms',
 'mptt',
 'debug_toolbar',
 'debug_toolbar_line_profiler',
 'template_timings_panel')
Installed Middleware:
(u'debug_toolbar.middleware.DebugToolbarMiddleware',
 'dogslow.WatchdogMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'pjax.middleware.PjaxMiddleware')

Traceback:
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  114.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/contrib/admin/options.py" in wrapper
  432.                 return self.admin_site.admin_view(view)(*args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  99.                     response = view_func(request, *args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  52.         response = view_func(request, *args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
  198.             return view(request, *args, **kwargs)
File "/Users/gwildorsok/Projects/*/src/*/admin.py" in change_view
  62.             request, object_id, form_url, extra_context=extra_context)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
  29.             return bound_func(*args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  99.                     response = view_func(request, *args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
  25.                 return func(self, *args2, **kwargs2)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/db/transaction.py" in inner
  399.                 return func(*args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/src/django-nested-inlines/nested_inlines/admin.py" in change_view
  262.                 self.save_model(request, new_object, form, True)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/contrib/admin/options.py" in save_model
  860.         obj.save()
File "/Users/gwildorsok/Projects/*/src/*/models.py" in save
  58.         super(*, self).save(*args, **kwargs)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/db/models/base.py" in save
  545.                        force_update=force_update, update_fields=update_fields)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/db/models/base.py" in save_base
  582.                                    update_fields=update_fields, raw=raw, using=using)
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/dispatch/dispatcher.py" in send
  185.             response = receiver(signal=self, sender=sender, **named)
File "/Users/gwildorsok/Projects/*/src/*/signals.py" in *
  14.     cache.clear()
File "/Users/gwildorsok/Projects/*/venv/lib/python2.7/site-packages/django/core/cache/backends/base.py" in clear
  193.         raise NotImplementedError

Exception Type: NotImplementedError at /admin/*
Exception Value:

Note that I censored some information.

And pip freeze:

Django==1.6.2
FeinCMS==1.9.3
MySQL-python==1.2.5
Pillow==2.2.2
South==0.8.4
Unidecode==0.04.14
amqp==1.4.3
anyjson==0.3.3
billiard==3.3.0.16
boto==2.23.0
celery==3.1.9
cssselect==0.9.1
decorator==3.4.0
django-celery==3.1.9
django-ckeditor-updated==4.2.8
django-debug-toolbar==1.0.1
django-debug-toolbar-line-profiler==0.4.0
django-debug-toolbar-template-timings==0.6
django-email-extras==0.2
django-forms-builder==0.10
django-mptt==0.6.0
-e git://github.com/Soaa-/django-nested-inlines.git@aaf995a223720ca7d6b4bfc74fb5707cd1bd08dd#egg=django_nested_inlines-dev
django-post-office==0.7.2
-e git://github.com/hmarr/django-ses@8a0377c40ad93f895dd7dd5f750501627f3cc78b#egg=django_ses-dev
django-storages==1.1.8
dogslow==0.9.7
feedparser==5.1.3
geopy==0.97
gunicorn==18.0
ipdb==0.8
ipython==1.1.0
jsonfield==0.9.20
kombu==3.0.12
line-profiler==1.0b3
lxml==3.3.0beta3
pyquery==1.2.8
pysolr==3.1.0
python-dateutil==2.2
python-gnupg==0.3.5
python-memcached==1.53
pytz==2013.9
raven==3.6.1
readline==6.2.4.1
redis==2.9.1
requests==2.2.0
six==1.5.2
sorl-thumbnail==11.12
sphinx-me==0.2.1
sqlparse==0.1.11
suds-jurko==0.6
wsgiref==0.1.2
xlrd==0.9.2

As you can see, it goes straight to the django.core.cache.backends.base.BaseCache.clear method, even though my backend setting is set to django.core.cache.backends.memcached.MemcachedCache. It works correctly with DDT turned off, I added a print in the clear method of the MemcachedCache class to confirm that.

aaugustin commented 10 years ago

Where does cache come from in this frame?

File "/Users/gwildorsok/Projects/*/src/*/signals.py" in *
  14.     cache.clear()

Gwildor commented 10 years ago

From from django.core.cache import cache

aaugustin commented 10 years ago

That's weird. I don't know how this could happen. Try inserting some debugging statements in debug_toolbar.panels.cache.CachePanel.enable/disable_instrumentation?

Gwildor commented 10 years ago

Really weird. I've set up a basic test project in an attempt to reproduce this problem in an isolated project, but I'm not able to. Tried different things, but everything up to clearing cache from inside a signal seems to work. When printing cache inside the signal I don't get CacheStatTracker either, just Django's MemcachedCache.

Being that I can't reproduce it, I'm closing this issue.

chrkr commented 9 years ago

It took me all of 10 minutes to find out why this was happening in my project, inside a view function:

the cache panel replaces the default cache (and the get_cache) function during the request middleware processing with CacheStatTracker/a function returning CacheStatTracker
processing continues until the actual view function is called
cache.clear() is called inside the view function, on CacheStatTracker
CacheStatTracker has no clear() method, but has inherited the clear() method from BaseCache
clear() is called on BaseCache
BaseCache raises NotImplementedError

You won't find this occurring outside a view function, because on the way back out, the processing passes through the debug toolbar middleware again, this time calling disable_instrumentation on the cache panel, which replaces the cache/get_cache with the original values again.

jazzband / django-debug-toolbar

NotImplementedError for cache clear #570