#5949: memory leak expose by elliptic curve code
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Reporter: mabshoff | Owner: mabshoff
Type: defect | Status: new
Priority: blocker | Milestone: sage-4.0
Component: memleak | Keywords:
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The following code consumes inordinate amounts of memory while Magma can
do it with 14 MB :)
{{{
p=30
def FindGroupOrder(p,s):
K = GF(p)
v = K(4*s)
u = K(s**2-5)
x = u**3
b = 4*x*v
a = (v-u)**3*(3*u+v)
A = a/b-2
x = x/v**3
b = x**3 + A*x**2 + x
E = EllipticCurve(K,[0,b*A,0,b**2,0])
return factor(E.cardinality())
while p<134217689:
p=next_prime(p)
g=FindGroupOrder(p,11)
print g
}}}
Valgrind pretty much points at libSingular (This was for running up to
2^12 or so):
{{{
==26879== 2,109,920 bytes in 469 blocks are possibly lost in loss record
14,860 of 14,862
==26879== at 0x4C22FEB: malloc (vg_replace_malloc.c:207)
==26879== by 0x1F1D0B3F: omAllocFromSystem (omAllocSystem.c:186)
==26879== by 0x1F1D0CC1: omAllocLarge (omAllocSystem.c:41)
==26879== by 0x1F0A0C2A: npInitChar(int, sip_sring*) (omalloc.h:2354)
==26879== by 0x1F0B817A: nInitChar(sip_sring*) (numbers.cc:506)
==26879== by 0x1F0C7197: rComplete(sip_sring*, int) (ring.cc:2922)
==26879== by 0x1ECBD1C7:
__pyx_pf_4sage_5rings_10polynomial_28multi_polynomial_libsingular_27MPolynomialRing_libsingular___init__(_object*,
_object*, _object*) (multi_polynomial_libsingular.cpp:4995)
==26879== by 0x45C040: type_call (typeobject.c:436)
==26879== by 0x417E92: PyObject_Call (abstract.c:1861)
==26879== by 0x485809: PyEval_EvalFrameEx (ceval.c:3784)
==26879== by 0x488296: PyEval_EvalFrameEx (ceval.c:3659)
==26879== by 0x489A95: PyEval_EvalCodeEx (ceval.c:2836)
==26879== by 0x487704: PyEval_EvalFrameEx (ceval.c:3669)
==26879== by 0x488296: PyEval_EvalFrameEx (ceval.c:3659)
==26879== by 0x489A95: PyEval_EvalCodeEx (ceval.c:2836)
==26879== by 0x4D40D7: function_call (funcobject.c:517)
==26879== by 0x417E92: PyObject_Call (abstract.c:1861)
==26879== by 0x41E6CE: instancemethod_call (classobject.c:2519)
==26879== by 0x417E92: PyObject_Call (abstract.c:1861)
==26879== by 0x485809: PyEval_EvalFrameEx (ceval.c:3784)
==26879== by 0x489A95: PyEval_EvalCodeEx (ceval.c:2836)
==26879== by 0x4D40D7: function_call (funcobject.c:517)
==26879== by 0x417E92: PyObject_Call (abstract.c:1861)
==26879== by 0x41E6CE: instancemethod_call (classobject.c:2519)
==26879== by 0x417E92: PyObject_Call (abstract.c:1861)
}}}
The above leak gets larger and larger depending on how I pick the upper
bound.
This translates to rings/polynomial/multi_polynomial_libsingular.pyx +359,
more specifically the rComplete() line in
{{{
self._ring.order[nblcks] = ringorder_C
rComplete(self._ring, 1)
self._ring.ShortOut = 0
}}}
From src/kernel/ring.h:
{{{
// this needs to be called whenever a new ring is created: new fields
// in ring are created (like VarOffset), unless they already exist
// with force == 1, new fields are _always_ created (overwritten),
// even if they exist
BOOLEAN rComplete(ring r, int force = 0);
}}}
Changing rComplete() to use 0 instead of 1 does not fix the problem.
Cheers,
Michael
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5949>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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