10.3. Valgrind

This is about how to build Valgrind, a Valgrind friendly version of Python and finally how to use and interpret Valgrind.

Note

These instructions have been tested on Mac OS X 10.9 (Mavericks). They may or may not work on other OS’s

10.3.1. Building Valgrind

This should be fairly straightforward:

svn co svn://svn.valgrind.org/valgrind
cd valgrind
./autogen.sh
./configure
make
make install

10.3.2. Building Python for Valgrind

Prepare the source by uncommenting Py_USING_MEMORY_DEBUGGER in Objects/obmalloc.c around line 1082 or so.

10.3.2.1. Configuring

configure takes the following aguments:

Argument

--enable-framework

Installs it in /Library/Frameworks/Python.framework/Versions/

--with-pydebug

Debug build of Python. See Misc/SpecialBuilds.txt

--without-pymalloc

With Valgrind support Misc/README.valgrind

To make a framework install:

./configure --enable-framework --with-pydebug --without-pymalloc --with-valgrind
sudo make frameworkinstall

To make a local version cd to the source tree and we will build a Valgrind version of Python in the valgrind/ directory:

mkdir valgrind
cd valgrind
../configure --with-pydebug --without-pymalloc --with-valgrind
make

10.3.2.1.1. Check debug build

$ python3 -X showrefcount

 1
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Python 3.4.3 (default, May 26 2015, 19:54:01)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.51)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 23
23
[54793 refs, 0 blocks]
>>> import sys
[54795 refs, 0 blocks]
>>> sys.gettotalrefcount()
54817
[54795 refs, 0 blocks]
>>> import sysconfig
>>> sysconfig.get_config_var('Py_DEBUG')
1

10.3.3. Using Valgrind

In the <Python source>/Misc directory there is a valgrind-python.supp file that supresses some Valgrind spurious warnings. I find that this needs editing so:

cp <Python source>/Misc/valgrind-python.supp ~/valgrind-python.supp
vi ~/valgrind-python.supp

Uncomment PyObject_Free and PyObject_Realloc in the valgrind suppression file.

Invoking the Python interpreter with Valgrind:

valgrind --tool=memcheck --dsymutil=yes --track-origins=yes --show-leak-kinds=all --trace-children=yes --suppressions=$HOME/.valgrind-python.supp <Python source>/valgrind/python.exe -X showrefcount

An example of using Valgrind to detect leaks is here: Finding Where the Leak is With Valgrind.