When I invoke a function like
BIG=myfunction(somevars)
where BIG gets to ~50% of RAM in a concrete case, re-running that function
again results in a memory error. If I release BIG first, say put BIG=0,
then it works. However, looking at top, I can see that only about half of
the memory allocated in the first call was actually released when I
clobbered BIG. So in the second case the memory usage first dropped to
about 25% of RAM and then ended at about 75% (and produced the correct
result btw). My RAM is 4G so we are talking about 1G gone missing after
BIG=0.
I attach the memory failure report but I don't think it is really relevant
here. Nothing was done before invoking myfunction(), except to load its
definition. Of course it consists of lots of things calling each other, but
the point here is that in the actual session, the only variable I hold on
to is BIG itself. I think that releasing BIG should then involve a cascade
of releasing the hidden variables.
I wonder if the developers think this is a bug. From the user's point of
view it is certainly strange that one cannot invoke the same function call
twice in a row.
Denis
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/opt/Sage/sage-7.0/src/sage/matrix/matrix2.pyx in
sage.matrix.matrix2.Matrix.right_kernel_matrix
(/opt/Sage/sage-7.0/src/build/cythonized/sage/matrix/matrix2.c:26391)()
3628 if M is None:
3629 try:
-> 3630 format, M =
self._right_kernel_matrix(algorithm=algorithm, proof=proof)
3631 except AttributeError:
3632 pass
/opt/Sage/sage-7.0/src/sage/matrix/matrix_rational_dense.pyx in
sage.matrix.matrix_rational_dense.Matrix_rational_dense._right_kernel_matrix
(/opt/Sage/sage-7.0/src/build/cythonized/sage/matrix/matrix_rational_dense.c:14282)()
1283 else:
1284 A, _ = self._clear_denom()
-> 1285 K = A._rational_kernel_iml().transpose().change_ring(QQ)
1286 verbose("done computing right kernel matrix over the rationals
for %sx%s matrix" % (self.nrows(), self.ncols()),level=1, t=tm)
1287 return 'computed-iml-rational', K
/opt/Sage/sage-7.0/src/sage/matrix/matrix_integer_dense.pyx in
sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml
(/opt/Sage/sage-7.0/src/build/cythonized/sage/matrix/matrix_integer_dense.c:31763)()
3647 cdef mpz_t *mp_N
3648 time = verbose('computing null space of %s x %s matrix using
IML'%(self._nrows, self._ncols))
-> 3649 self._init_mpz()
3650 sig_on()
3651 dim = nullspaceMP(self._nrows, self._ncols, self._entries,
&mp_N)
/opt/Sage/sage-7.0/src/sage/matrix/matrix_integer_dense.pyx in
sage.matrix.matrix_integer_dense.Matrix_integer_dense._init_mpz
(/opt/Sage/sage-7.0/src/build/cythonized/sage/matrix/matrix_integer_dense.c:6207)()
223 return 0
224 else:
--> 225 return self._init_mpz_impl()
226
227 cdef inline int _init_linbox(self) except -1:
/opt/Sage/sage-7.0/src/sage/matrix/matrix_integer_dense.pyx in
sage.matrix.matrix_integer_dense.Matrix_integer_dense._init_mpz_impl
(/opt/Sage/sage-7.0/src/build/cythonized/sage/matrix/matrix_integer_dense.c:6421)()
241 if not self._entries:
242 sage_free(self._rows)
--> 243 raise MemoryError
244 k = 0
245 for i in range(self._nrows):
MemoryError:
