missing dictionary deallocation in Cython's init code

[mabshoff]

Okay, the problem I found is deep in Cython generated code and maybe not the fault of Cython, but might be an underlying issue in Python. For each of the 244 pyx files we have in the tree we do not deallocate a dictionary. While this isn't a defect per se it makes the valgrind output more noise and therefor more difficult to parse.

The example output below is from rational.pyx. The function initrational is created via Cython (there is no init-method, but that comes out of the creation of the class as far as I can tell):

==25825== 3,072 bytes in 1 blocks are still reachable in loss record 2,268 of 2,539
==25825==    at 0x4A05809: malloc (vg_replace_malloc.c:149)
==25825==    by 0x43F179: dictresize (dictobject.c:513)
==25825==    by 0x45B00C: PyType_Ready (typeobject.c:5575)
==25825==    by 0x169D79A0: initrational (rational.c:10789)
==25825==    by 0x49F762: _PyImport_LoadDynamicModule (importdl.c:53)
==25825==    by 0x49D63E: import_submodule (import.c:2394)
==25825==    by 0x49DB11: load_next (import.c:2214)
==25825==    by 0x49DD6E: import_module_level (import.c:2002)
==25825==    by 0x49E1A4: PyImport_ImportModuleLevel (import.c:2066)
==25825==    by 0x47D5D8: builtin___import__ (bltinmodule.c:47)
==25825==    by 0x4156A2: PyObject_Call (abstract.c:1860)
==25825==    by 0x47DB71: PyEval_CallObjectWithKeywords (ceval.c:3433)

The exact line from rational.c:10789 is:

if (PyType?_Ready(&pyx_type_8rational_Rational) < 0) {pyx_filename = pyx_f[1]; pyx_lineno = 126; goto pyx_L1;}

It mentions line 126 which in rational.pyx is:

cdef class Rational(sage.structure.element.FieldElement?):

So can be dereference the class somehow upon exit? Looking at valgrind-sessions from python it appears that this is possible because otherwise there would be a large number of leak dictionaries from the buildin c-libraries.

Cheers,

Michael

[mabshoff]

The link to the discussion in sage-devel is

 http://groups.google.com/group/sage-devel/t/673812f3d9ed262a

Cheers,

Michael

[mabshoff]

For some more discussion and a potential cause check out

 http://groups.google.com/group/sage-devel/t/5a1d104614ced3aa

Cheers,

Michael