#11521: Use weak references to cache homsets
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Reporter: jpflori | Owner: robertwb
Type: defect | Status:
positive_review
Priority: major | Milestone: sage-5.4
Component: coercion | Resolution:
Keywords: sd35 | Work issues:
Report Upstream: N/A | Reviewers: Jean-Pierre
Flori, Nils Bruin
Authors: Simon King | Merged in:
Dependencies: #12969; to be merged with #715 | Stopgaps:
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Comment (by jpflori):
Replying to [comment:155 nbruin]:
relevance to that case. Once a coercion `h: X -> Y` is discovered, a
strong reference to `h` is stored in `self._coerce_from_hash`. Since `h`
stores a strong reference to `X` we now have ensured that the life time of
`X` is bounded below by the life time of `Y`. So the weak caching there
only helps for `X` that do not coerce into `Y`.
>
> How eagerly does the system use the `self._convert_from_hash`? It is
quite likely that even with #12313 in place,
> {{{#!python
> for p in prime_range(1,1000):
> k=GF(p)
> a=k(1)
> b=ZZ(a)
> }}}
I see the problem.
Another solution may be to use TripleDicts there as well rather than
MonoDicts.
Or DuoDicts!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11521#comment:157>
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