Hi!
In the attempt to hunt down a memleak in my cohomology package, I
found something that I can't understand. Can you perhaps explain what
happens?
Put the following code into a file int2Z.pyx:
def test(N):
cdef int i
for i from 0 <= i <= N:
a += 1 # just in order to avoid that the loop is empty
Now, after installing the valgrind-spkg and doing sage -ba, I did the
following on an Intel Core Duo with GNU Linux:
> sage -valgrind
----------------------------------------------------------------------
| Sage Version 4.1, Release Date: 2009-07-09 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
/home/king/SAGE/sage-4.1/local/bin/sage-ipython
Log file is /home/king/.sage/valgrind/sage-memcheck.%p
Using default flags:
--leak-resolution=high --log-file=/home/king/.sage/valgrind/sage-
memcheck.%p --leak-check=full --num-callers=25 --suppressions=/home/
king/SAGE/sage-4.1/local/lib/valgrind/sage.supp
Python 2.6.2 (r262:71600, Jul 27 2009, 13:41:09)
[GCC 4.3.1 20080507 (prerelease) [gcc-4_3-branch revision 135036]] on
linux2
Type "help", "copyright", "credits" or "license" for more information.
sage: attach int2Z.pyx
Compiling /home/king/tests/int2Z.pyx...
sage: test(100000)
sage: quit
Exiting SAGE (CPU time 0m1.79s, Wall time 0m9.32s).
I put the valgrind log at
http://sage.math.washington.edu/home/SimonKing/logs/memcheck.int2Integer
This simple code results in:
==26929== LEAK SUMMARY:
==26929== definitely lost: 8 bytes in 1 blocks.
==26929== possibly lost: 436,049 bytes in 1,043 blocks.
==26929== still reachable: 49,247,285 bytes in 30,191 blocks.
If I interprete the valgrind log correctly, the problem is the
conversion of a python integer to an Integer. Therefore I tested
various modifications of the code, e.g.,
def test(int N):
cdef int i
cdef int a=0
for i from 0 <= i <= N:
a += 1 # just in order to avoid that the loop is empty
But this didn't help.
Questions:
- Note that valgrind says "Log file is /home/king/.sage/valgrind/sage-
memcheck.%p". It does *not* say what number "%p" refers to. Bug?
- The code is very simple and probably ubiquitous in the sage
library. Hence I can hardly believe that there is a memory leak on
such a basic level without being noticed by many people. Did I
misinterpret the valgrind log?
Cheers,
Simon
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