#12215: Memleak in UniqueRepresentation, @cached_method
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Reporter: vbraun | Owner: rlm
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.8
Component: memleak | Keywords: UniqueRepresentation cached_method
caching
Work_issues: | Upstream: N/A
Reviewer: | Author: Simon King
Merged: | Dependencies: #11115 #11900
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Changes (by SimonKing):
* cc: vbraun (added)
Comment:
Cc to Volker, because I expect he has enough knowledge to give me some
advice on how I could trace down the following segfault.
With #12313 and the patch from here, `sage -t -verbose -force_lib
"devel/sage/doc/en/bordeaux_2008/half_integral.rst"` segfaults. By
inspection of the core file, I found that the segfault occurs during
deallocation of a functor.
For debugging, I added a `__dealloc__` method to
`sage.categories.functor.Functor` that writes the type and the address of
self and of the two cdef attributes `__domain` and `__codomain` to some
file. The same is done during initialisation of the functor.
And the last lines of the resulting file (before the segfault) are:
{{{
Dealloc Functor <type 'sage.structure.coerce_actions.LeftModuleAction'> at
71023056
Domain <class 'sage.categories.groupoid.Groupoid'> at 75636560
Codom. <class 'sage.categories.commutative_rings.CommutativeRings'> at
15429144
Dealloc Functor <type 'sage.structure.coerce_actions.LeftModuleAction'> at
71023056
Domain <type 'NoneType'> at 140661532564960
Codom. <type 'NoneType'> at 140661532564960
}}}
In other words, the functor is deallocated twice, which is a legitimate
reason to segfault.
How can I find out why Sage tries to deallocate it twice?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12215#comment:53>
Sage <http://www.sagemath.org>
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