#14711: Memleak when creating QuadraticField
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Reporter: jpflori | Owner:
Type: defect | davidloeffler
Priority: critical | Status: new
Component: number fields | Milestone: sage-5.12
Keywords: memleak, number field, | Resolution:
QuadraticField | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: u/SimonKing/ticket/14711 | Commit:
Dependencies: | Stopgaps:
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Comment (by SimonKing):
With the following done, Sage starts:
- Having the usual strong references of homsets to domain and codomain.
- Having maps by default as "usual" elements with strong references to
domain and codomain.
- `self._parent=None` for maps registered by the coercion model,
overriding the `self.parent()` method by something that tries to
reconstruct the parent from domain and codomain.
Moreover, it fixes the memleak:
{{{
sage: Q = QuadraticField(-5)
sage: C = Q.__class__.__base__
sage: import gc
sage: _ = gc.collect()
sage: numberQuadFields = len([x for x in gc.get_objects() if isinstance(x,
C)])
sage: del Q
sage: _ = gc.collect()
sage: numberQuadFields == len([x for x in gc.get_objects() if
isinstance(x, C)]) + 1
True
}}}
Granted, it is possible to get a map in an invalid state (at least with
the not-yet-posted version of my branch):
{{{
sage: Q = QuadraticField(-5)
sage: phi = CDF.convert_map_from(Q)
sage: del Q
sage: _ = gc.collect()
sage: phi.parent()
---------------------------------------------------------------------------
ValueError Traceback (most recent call
last)
<ipython-input-14-5708ddd58791> in <module>()
----> 1 phi.parent()
/home/king/Sage/git/sage/local/lib/python2.7/site-
packages/sage/categories/map.so in sage.categories.map.Map.parent
(sage/categories/map.c:3023)()
ValueError: This map is in an invalid state, domain or codomain have been
garbage collected
}}}
But the question is: Is there any way to make Q garbage collectable in the
first example but not collectable in the second example?
--
Ticket URL: <http://trac.sagemath.org/ticket/14711#comment:45>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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