Re: Tuple size and memory allocation for embedded Python

[Steve Holden]

Jinming Xu wrote:
Hi Folks,
Python seems unstable, when allocating big memory.  For example, the 
following C++ code creates a tuple of tuples:

 PyObject* arCoord = PyTuple_New(n);
 double d = 1.5;
 for(int i=0; i<n; i++)
   {
     PyObject* coord = PyTuple_New(2);
     PyTuple_SetItem(coord,0, PyFloat_FromDouble(d));//x
     PyTuple_SetItem(coord,1, PyFloat_FromDouble(d));//y
     PyTuple_SetItem(arCoord,i, coord);
   }
When the n is small, say 100, the code works fine.  when n is big, say 
10,000, Python has trouble allocating memory, saying:

"Exception exceptions.IndexError: 'tuple index out of range' in 'garbage 
collection' ignored
Fatal Python error: unexpected exception during garbage collection
Aborted"

Could anyone please give me some insight or a fix for this?
Thanks in advance for your answer.
I'm going to guess that the problem is related to incorrect reference 
counts. I don't see any IncRefs in there. It seems probable that the 
program will work until you make n high enough to trigger a garbage 
collection sweep, then memory your program still regards as allocated is 
garbage collected by Python and reused. Ugly :-P

Python is pretty stable, so it's usually best to suspect our own code 
unless you're heavily into using the C API (which I'm not, so feel free 
to ignore me).

regards
 Steve
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