Some doc request hangs sage eating all memory

[hivert]

If I type

sage: MS = MatrixSpace(QQ,6,6,sparse=True); MS
Full MatrixSpace of 6 by 6 sparse matrices over Rational Field
sage: MS?

Then sage hangs eating all the memory. I don't have the less idea why it happens with MatrixSpace. I didn't try very hard but I can't manage any other request with the same effect. I checked that this is not a problem of installation on my computer: It happens as well on boxen. Though, on the contrary to my own computer, I didn't check that it effectively eat all the memory on boxen ;-)

Cheers,

Florent

[was]

I can confirm this bug on the command line. However, not interestingly that it does *not* happen in the Sage notebook. So it is an Ipython bug.

 http://wstein.org/home/wstein/patches/trac_7449.png

[hivert]

Replying to was:

I can confirm this bug on the command line. However, not interestingly that it does *not* happen in the Sage notebook. So it is an Ipython bug.

 http://wstein.org/home/wstein/patches/trac_7449.png

So what should we do ? Try to figure out a smaller file that triggers the problem and report to the ipython community ? I've no idea how to debug ipython. Any better suggestion ?

[was]

Fernando Perez solved the problem:

On Mon, Nov 16, 2009 at 2:31 AM, Fernando Perez
<> wrote:
> The fact that Ctrl-C cleanly stops the crazy loop *without* a
> KeyboardInterrupt makes me think that ipython is trying to introspect
> the MS object and some C code is going into a mad loop (otherwise we'd
> see the Python signal handler showing a traceback).  Do you have any
> other bugs related to this type of object that sound along those
> lines?

Half-right. IPython is swallowing the kbd interrupt, but the bug is in
sage, it's the fact that len(MS) never returns:

sage: MS = MatrixSpace(QQ,6,6,sparse=True); MS
Full MatrixSpace of 6 by 6 sparse matrices over Rational Field
sage: len(MS)
^C---------------------------------------------------------------------------
KeyboardInterrupt                         Traceback (most recent call last)

/home/fperez/ipython/repo/kernel-config-lp/docs/<ipython console> in <module>()

/opt/sage/local/lib/python2.6/site-packages/sage/structure/parent.so
in sage.structure.parent.Parent.__len__
(sage/structure/parent.c:5533)()

/opt/sage/local/lib/python2.6/site-packages/sage/structure/parent.so
in sage.structure.parent.Parent.list (sage/structure/parent.c:4995)()

/opt/sage/local/lib/python2.6/site-packages/sage/matrix/matrix_space.pyc
in __iter__(self)
   751             while True:
   752                 for iv in
sage.combinat.integer_vector.IntegerVectors(weight,
number_of_entries):
--> 753                     yield self(entries=[base_elements[i] for i
in iv], rows=True)
   754
   755                 weight += 1

/opt/sage/local/lib/python2.6/site-packages/sage/matrix/matrix_space.pyc
in __call__(self, entries, coerce, copy, rows)
   371             copy = False
   372         elif self.__is_sparse and isinstance(entries, (list, tuple)):
--> 373             entries = list_to_dict(entries, self.__nrows,
self.__ncols, rows=rows)
   374             coerce = True
   375             copy = False

/opt/sage/local/lib/python2.6/site-packages/sage/matrix/matrix_space.pyc
in list_to_dict(entries, nrows, ncols, rows)
  1240                 d[(row,col)] = x
  1241             else:
-> 1242                 d[(col,row)] = x
  1243     return d
  1244

/opt/sage/local/lib/python2.6/site-packages/sage/interfaces/get_sigs.pyc
in my_sigint(x, n)
     7
     8 def my_sigint(x, n):
----> 9     raise KeyboardInterrupt
    10
    11 def my_sigfpe(x, n):

KeyboardInterrupt:


It seems that the ms object implements __len__, but this function
never returns.  It's just that ipython was calling len() on it.

Cheers,

f

[hivert]

Replying to was:

It seems that the ms object implements len, but this function never returns. It's just that ipython was calling len() on it.

Good remark ! This indicate that there should be a generic test in the base category Objects() checking that for the current object __len__ is either not defined either returns a correct int object or else raise an exception. Any other behavior (loop, returning a sage Integer or any fancy object should be reported as an error).

Those bugs seems therefore catchable by TestSuite if the object correctly inherits from the good category. I'll try it.

Otherwise positive review.

Cheers,

Florent