How can I use valgrind with Python C++ extensions?

Question

I have Python extensions implemented on C++ classes. I don't have a C++ target to run valgrind with. I want to use valgrind for memory check.

Can I use valgrind with Python?

Answer 1

Yes, you can use valgrind with Python. You just need to use the valgrind suppression file provided by the Python developers, so you don't get a bunch of false positives due to Python's custom memory allocation/reallocation functions.

The valgrind suppression file can be found here: http://svn.python.org/projects/python/trunk/Misc/valgrind-python.supp

IMPORTANT: You need to uncomment the lines for PyObject_Free and PyObject_Realloc in the suppression file*.

The recommended usage syntax is:

$ valgrind --tool=memcheck --suppressions=valgrind-python.supp 
                                          python -E -tt ./my_python_script.py

See also this README file from the Python SVN repo which describes the different ways of using Python with valgrind: http://svn.python.org/projects/python/trunk/Misc/README.valgrind

* - Alternatively, you can recompile Python with PyMalloc disabled, which allows you to catch more memory leaks that won't show up if you just suppress PyMalloc.