Have you ruled out the possibility that collections.Mapping has been (perhaps temporarily) assigned to something else?
On Thu, Jan 18, 2018 at 2:37 PM, Jason Swails <jason.swa...@gmail.com> wrote: > Hello! > > I am running into a very perplexing issue that is very rare, but creeps up > and is crashing my app. > > The root cause of the issue comes down to the following check returning > true: > > isinstance([], collections.Mapping) > > Obviously you can get this behavior if you register `list` as a subclass of > the Mapping ABC, but I'm not doing that. Because the issue is so rare (but > still common enough that I need to address it), it's hard to reproduce in a > bench test. > > What I am going to try is to essentially monkey-patch > collections.Mapping.register with a method that dumps a stack trace > whenever it's called at the time of initial import so I can get an idea of > where this method could *possibly* be getting called with a list as its > argument. > > The annoying thing here is that wherever the bug is happening, the crash > happens *way* far away (in a third-party library). I've also determined it > as the root cause of two crashes that seem completely unrelated (except > that the crash is caused by a list not behaving like a dict shortly after > isinstance(obj, collections.Mapping) returns True). These are the > libraries I'm using: > > amqp > billiard > celery > dj-database-url > Django > django-redis-cache > enum34 > gunicorn > kombu > newrelic > psycopg2 > pyasn1 > pytz > redis > requests > rsa > six > vine > voluptuous > > It's a web application, as you can probably tell. The main reason I ask > here is because I'm wondering if anybody has encountered this before and > managed to hunt down which of these libraries is doing something naughty? > > Thanks! > Jason > > -- > Jason M. Swails > -- > https://mail.python.org/mailman/listinfo/python-list > -- https://mail.python.org/mailman/listinfo/python-list
