#14471: Exception KeyError: in WeakValueDictionary remove ignored
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Reporter: vbraun | Owner: rlm
Type: defect | Status: new
Priority: major | Milestone: sage-5.10
Component: memleak | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by nbruin):
Replying to [comment:10 vbraun]:
> As for Sage, should we patch Python for this? I hit this bug in #14469
and its likely that we'll trip over it again.
I would suggest a paranoid `remove` function for this:
{{{
def remove(wr, selfref=ref(self)):
self = selfref()
if self is not None and self.data.get(wr.key) is wr:
del self.data[wr.key]
}}}
The `get` method avoids exception handling and hopefully avoids allocation
as much as possible (thus avoiding triggering GC) and will return `None`
if the reference is not present. Furthermore, we verify that the correct
value is still stored in the dictionary, in case a callback gets delayed
so much that another value makes it into that dict under the same key
(that shouldn't really happen, so that's the paranoid bit).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14471#comment:11>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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