#10963: More functorial constructions
-------------------------------------+-------------------------------------
Reporter: nthiery | Owner: stumpc5
Type: enhancement | Status: needs_work
Priority: major | Milestone:
Component: categories | Resolution:
Keywords: | Merged in:
Authors: Nicolas M. Thiéry | Reviewers: Simon King
Report Upstream: N/A | Work issues: Reduce startup time
Branch: | by 5%. Avoid "recursion depth
Dependencies: #11224, #8327, | exceeded (ignored)".
#10193, #12895, #14516, #14722, | Commit:
#13589, #14471 | Stopgaps:
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Comment (by nthiery):
Ok, from Volker's suggestion on Sage-devel, one can raise a similar error
message when garbage collecting the entries of a MonoDict (would be the
same with a tripledict) involves a big recursion because deleting an entry
triggers the deletion of another entry and so on:
{{{
from sage.structure.coerce_dict import MonoDict
M = MonoDict(11)
class A: pass
a = A()
prev = a
for i in range(1000):
newA = A()
M[prev] = newA
prev = newA
len(M)
del a
Exception RuntimeError: 'maximum recursion depth exceeded while calling a
Python object' in <sage.structure.coerce_dict.MonoDictEraser object at
0x5a13788> ignored
}}}
At this point, my guess is that our weak dictionary infrastructure
currently has an intrisic limitation on the depth of the reference graph,
and that all the functioral construction patch does is putting a bit more
stress and reach this limitation. So now the question is: is it possible
to fix the weak dict infrastructure to let it scale properly by somehow
unrolling the recursion as Volker suggests in [1].
Cheers,
[1] https://groups.google.com/d/msg/sage-devel/us0JCrRwGz0/McDlwepFve4J
--
Ticket URL: <http://trac.sagemath.org/ticket/10963#comment:91>
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