[issue27275] KeyError thrown by optimised collections.OrderedDict.popitem()
Raymond Hettinger
report at bugs.python.org
Fri Jun 10 13:31:59 EDT 2016
Raymond Hettinger added the comment:
I'm wondering if the expiringdict(1) needs to have locked wrappers for the inherited methods:
def __delitem__(self, key):
with self.lock:
OrderedDict.__delitem__(self, key)
Otherwise, there is a risk that one thread is deleting a key with no lock held, while another thread is running expiringdict.popitem() which holds a lock while calling both __getitem__ and del. If the first thread runs between the two steps in the second, the race condition would cause a KeyError.
This might explain why you've observed, '''Replacing use of popitem() with "del self[next(OrderedDict.__iter__(self))]" removes the KeyErrors and the structure otherwise works fine.'''
(1) https://github.com/mailgun/expiringdict/blob/master/expiringdict/__init__.py
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nosy: +rhettinger
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<http://bugs.python.org/issue27275>
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