#11967: os x 10.7 Lion -- Sage segfaults on startup when initializing GiNaC
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Reporter: was | Owner: drkirkby
Type: defect | Status: new
Priority: major | Milestone: sage-4.7.3
Component: porting | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by was):
I looked into this further, but haven't solved the problem. I made an
*empty* Cython file a.pyx with Extension description:
{{{
Extension('sage.symbolic.a',
sources = ['sage/symbolic/a.pyx'],
language = 'c++',
depends = ginac_depends,
libraries = ["pynac", "gmp"]),
}}}
then I did "sage -ipython" and "import sage.symbolic.a", and I get exactly
the same crash as when import sage.all.
I looked at the traceback more carefully. The line
{{{
#0 PyInt_FromLong (ival=Cannot access memory at address 0x0
) at intobject.c:91
}}}
occurs in the Python library in this code:
{{{
#if NSMALLNEGINTS + NSMALLPOSINTS > 0
if (-NSMALLNEGINTS <= ival && ival < NSMALLPOSINTS) {
v = small_ints[ival + NSMALLNEGINTS];
Py_INCREF(v);
<------------------------ ***
#ifdef COUNT_ALLOCS
}}}
Thus the array small_ints -- this is some "object pool" (maybe) -- hasn't
been initialized.
This was called from the Pynac library on startup where various constants
(e.g., 1,2,3,4,5, etc., ) are defined. In particular, this line in
pynac's numeric.cpp causes the trouble:
{{{
t = PYOBJECT;
if (!(v._pyobject = PyInt_FromLong(x)))
py_error("Error creating int");
}}}
This *feels* to me a lot like what would happen if two separate copies of
the Python library were linked in. One of them hasn't been initialized
yet, so the object pool is nonsense. However, I don't see a static
libpython sitting around anywhere, so I'm not quite sure what happened.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11967#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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