#26152: django.setup() hangs django if ever used in a module that's imported by
an
app
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Reporter: hjwp | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Documentation | Version: 1.9
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by hjwp):
Just been digging into this. And I am not an experienced coder of
multithreaded code, so I probably shouldn't be allowed.
Here's the current code:
{{{
# populate() might be called by two threads in parallel on servers
# that create threads before initializing the WSGI callable.
with self._lock:
if self.ready:
return
# app_config should be pristine, otherwise the code below
won't
# guarantee that the order matches the order in
INSTALLED_APPS.
if self.app_configs:
raise RuntimeError("populate() isn't reentrant")
# [...] rest of populate code
self.ready = True
}}}
So switching _lock to being a threading.RLock will have the desired effect
of raising the "populate isn't reentrant" exception that's already been
defined, if populate is ever called recursively by the same thread.
I'm not sure I understand the code though. Under what circumstances, with
the current threading.Lock(), would we expect the RuntimeError to be
encountered?
--
Ticket URL: <https://code.djangoproject.com/ticket/26152#comment:9>
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