Possible Bug in RegexURLResolver

[a.br...@rataran.com]

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

[Markus Holtermann]

Hey,

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

Thanks

/Markus

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