#29403: TooBig error in memcached
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
SKisContent |
Type: Bug | Status: new
Component: Core | Version: 1.11
(Cache system) |
Severity: Normal | Keywords: memcached, TooBig
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I'm trying to use the memcached backend cache in a project, and I'm get a
TooBig error on some requests. The error occurs in
''django/core/cache/backends/memcached.py'' on line 86:
{{{
val = self._cache.get(key)
if val is None:
return default
return val
def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
key = self.make_key(key, version=version)
** if not self._cache.set(key, value,
self.get_backend_timeout(timeout)):**
# make sure the key doesn't keep its old value in case of
failure to set (memcached's 1MB limit)
self._cache.delete(key)
def delete(self, key, version=None):
key = self.make_key(key, version=version)
self._cache.delete(key)
}}}
I can reproduce it using the Django shell:
{{{
$ ./manage.py shell
Python 2.7.12 (default, Nov 19 2016, 06:48:10)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from django.core.cache import cache
>>> cache.get('foo')
>>> cache.set('foo', 'bar')
>>> cache.get('foo')
'bar'
>>> big = [i for i in range(1024*1024)]
>>> cache.set('big_foo', big)
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/local/lib/python2.7/site-
packages/django/core/cache/backends/memcached.py", line 86, in set
if not self._cache.set(key, value, self.get_backend_timeout(timeout)):
TooBig
}}}
I can replicate the same behavior in pylibmc:
{{{
$ python
Python 2.7.12 (default, Nov 19 2016, 06:48:10)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from pylibmc.test import make_test_client
>>> mc = make_test_client()
>>> mc.get('foo')
>>> mc.set('foo', 'bar')
True
>>> mc.get('foo')
'bar'
>>> big = [i for i in range(1024*1024)]
>>> mc.set('big_foo', big)
Traceback (most recent call last):
File "<console>", line 1, in <module>
TooBig
}}}
The TooBig exception was added to pylibmc in 2016:
[https://github.com/lericson/pylibmc/commit/736e21276ad04d557b68bd81b7f28be1a4b4e1ec]
The uncaught error breaks the application. Looking at the comment about
the 1MB size limit on the next line (line 87), it seems like the original
intent was to unset the value and fail silently. Therefore, the **if**
block needs to be wrapped in **try...except**.
--
Ticket URL: <https://code.djangoproject.com/ticket/29403>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/054.4c3454721be80373eef750c11a0b0d7f%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.
