#15618: Use the correct categories for coercion and conversion maps
-------------------------------------+-------------------------------------
Reporter: pbruin | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: coercion | Resolution:
Keywords: conversion map | Merged in:
Authors: Peter Bruin | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/pbruin/15618-DefaultConvertMap | 54a6ecae11f902b11ad651c67af021af6ed2da21
Dependencies: #16401, #16402, | Stopgaps:
#17359 |
-------------------------------------+-------------------------------------
Comment (by nbruin):
Just this line:
{{{
if
category.is_subcategory(FiniteDimensionalAlgebrasWithBasis(self.base_ring()))
}}}
is a memory leak:
{{{
sage: import gc
sage: from collections import Counter
sage: gc.collect()
93
sage: pre={id(a) for a in gc.get_objects()}
sage:
sage: for p in prime_range(20000):
....: A = FiniteDimensionalAlgebrasWithBasis(GF(p))
....:
sage: gc.collect()
0
sage: post=Counter(str(type(a)) for a in gc.get_objects() if id(a) not in
pre)
sage: post
Counter({"<type 'tuple'>": 314633, "<type 'dict'>": 106360, "<type
'list'>": 88464, "<type 'cell'>": 67894, "<type
'sage.misc.cachefunc.CachedMethodCallerNoArgs'>": 52032, "<type
'weakref'>": 40733, "<class 'weakref.KeyedRef'>": 36193, "<type
'function'>": 33947, "<type 'staticmethod'>": 33947, "<type
'builtin_function_or_method'>": 33938, "<type
'sage.misc.cachefunc.CachedMethodCaller'>": 33937, "<type 'frozenset'>":
33933, "<class 'sage.structure.dynamic_class.DynamicClasscallMetaclass'>":
33932, "<type 'sage.rings.finite_rings.integer_mod.IntegerMod_int'>":
25868, "<type 'sage.structure.coerce_dict.MonoDict'>": 4522, "<type
'sage.structure.coerce_dict.MonoDictEraser'>": 4522, "<class
'sage.categories.unital_algebras.UnitalAlgebras_with_category'>": 2262,
"<class
'sage.categories.vector_spaces.VectorSpaces.WithBasis_with_category'>":
2262, "<class 'sage.categories.bimodules.Bimodules_with_category'>": 2262,
"<class
'sage.categories.unital_algebras.UnitalAlgebras.WithBasis_with_category'>":
2262, "<class 'sage.categories.algebras.Algebras_with_category'>": 2262,
"<class 'sage.categories.left_modules.LeftModules_with_category'>": 2262,
"<class 'sage.categories.vector_spaces.VectorSpaces_with_category'>":
2262, "<class
'sage.categories.right_modules.RightModules_with_category'>": 2262,
"<class
'sage.categories.finite_dimensional_algebras_with_basis.FiniteDimensionalAlgebrasWithBasis_with_category'>":
2262, "<class
'sage.categories.modules_with_basis.ModulesWithBasis_with_category'>":
2262, "<class
'sage.categories.algebras_with_basis.AlgebrasWithBasis_with_category'>":
2262, "<class
'sage.categories.magmatic_algebras.MagmaticAlgebras.WithBasis_with_category'>":
2262, "<class
'sage.categories.associative_algebras.AssociativeAlgebras_with_category'>":
2262, "<class 'sage.categories.modules.Modules_with_category'>": 2262,
"<type 'sage.structure.coerce_dict.TripleDict'>": 2261, "<class
'sage.rings.ideal.Ideal_pid'>": 2261, "<type
'sage.rings.finite_rings.integer_mod.NativeIntStruct'>": 2261, "<class
'sage.categories.magmatic_algebras.MagmaticAlgebras_with_category'>":
2261, "<class
'sage.rings.finite_rings.finite_field_prime_modn.FiniteField_prime_modn_with_category'>":
2261, "<type 'sage.structure.coerce_dict.TripleDictEraser'>": 2261, "<type
'instancemethod'>": 2261, "<class
'sage.structure.dynamic_class.DynamicMetaclass'>": 15, "<class
'_ast.Call'>": 3, "<type 'sage.misc.constant_function.ConstantFunction'>":
2, "<class '_ast.Name'>": 2, "<type 'frame'>": 1, "<type 'set'>": 1,
"<class '_ast.comprehension'>": 1, "<class '_ast.Interactive'>": 1,
"<class
'sage.categories.finite_dimensional_modules_with_basis.FiniteDimensionalModulesWithBasis_with_category'>":
1, "<class '_ast.Module'>": 1, "<type
'sage.categories.category_singleton.Category_contains_method_by_parent_class'>":
1, "<type 'listiterator'>": 1, "<type 'generator'>": 1, "<class
'_ast.Assign'>": 1, "<class
'sage.categories.modules.Modules.FiniteDimensional_with_category'>": 1})
}}}
The problem is that categories themselves have infinite life, so one
should not instantiate parametrized categories unless one really has to.
To this end we now have:
{{{
sage: GF(3)['x'].category()
Join of Category of euclidean domains and Category of commutative algebras
over (finite fields and subquotients of monoids and quotients of
semigroups)
}}}
(as you can see, the category doesn't explicitly link to `GF(3)` anymore)
Admittedly:
{{{
sage: FiniteDimensionalAlgebra(GF(3), [Matrix([[1, 0], [0, 1]]),
Matrix([[0, 1], [0, 0]])]).category()
Category of finite dimensional algebras with basis over Finite Field of
size 3
}}}
so the memory leak already exists for `FiniteDimensionalAlgebra` in
general. However, since you're introducing the line here, you should
probably argue why you're not making the problem worse and/or open a
ticket about the memory leak in general.
--
Ticket URL: <http://trac.sagemath.org/ticket/15618#comment:32>
Sage <http://www.sagemath.org>
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