Re: Possible Bug in RegexURLResolver

Hey,

I did indeed not consider the multi-threading behavior on uwsgi when
writing that. Can you post this to django-developers@googlegroups.com
and open a ticket for that. I'd love to get someone else's input.

Thanks

/Markus

On Sat, Jul 09, 2016 at 08:36:44AM -0700, a.branco@rataran.com wrote:
>Hello everyone.
>
>I'm using django (1, 10, 0, u'beta', 1).
>
>When I try to reverse url in shell everything goes fine.
>
>When under nginx/uwsgi with many concurrent request I get
>
>... /local/lib/python2.7/site-packages/django/urls/resolvers.py", line 241,
>in reverse_dict
> return self._reverse_dict[language_code]
>KeyError: 'it'
>
>After a wile I figured out that RegexURLResolver is memoized by
>get_resolver and so it acts like a singleton for a certain number of
>requests.
>
>Analyzing the code of RegexURLResolver I found that the method _poupulate
>will return directly if it has been called before and not yet finished.
>
> ...
> def _populate(self):
> if self._populating:
> return
> self._populating = True
> ...
>
>if used for recursive call in a single thread this will not hurt, but in my
>case in uwsgi multi thread mode I got the error.
>
>here is my quick and dirty fix:
>
>class RegexURLResolver(LocaleRegexProvider):
> def __init__(self, regex, urlconf_name, default_kwargs=None,
>app_name=None, namespace=None):
>
> ...
>
> self._populating = False
> self.RLock = threading.RLock()
>
> ...
>
> def _populate(self):
> if self._populating:
> self.RLock.acquire()
> self.RLock.release()
> return
> self._populating = True
> self.RLock.acquire()
>
> ...
>
> self._populating = False
> self.RLock.release()
>
>
>Does anyone know if there is a better solution?
>
>Tank You
>
>
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