Question

I have a problem with a segfault in pyodbc and would like to debug it in Windows XP x86. However, the information online seems primarily Linux-centric. What is the best way to go about this?

Answer 1

So I was able to successfully resolve my issue by using Visual Studio 2008. I loosely followed the steps listed here –

http://www.velocityreviews.com/forums/t329214-debugging-python-extensions.html

And some tips on workarounds here –

Compiling python modules whith DEBUG defined on MSVC

Here is my version of the steps for anyone else who may encounter this problem.

1. In case you haven’t already, be sure to setup the Python header and libs directories in VS

   a. Go to Tools > Options > Projects and Solutions > VC++ Directories. Be sure to add your include and libs path to the Include and Library files’ path, respectively. (e.g. C:\Python27\include, C:\Python27\libs)

2. Go to your Python include folder (once again, e.g. C:\Python27\include) and edit pyconfig.h. Comment out the line # define Py_DEBUG and save. Go to your libs folder (e.g. C:\Python27\libs) and make a copy of python27.lib. Name the copy python27_d.lib.

3. Create a new project. Choose Win32 Project and name it the module name (in my case pyodbc. Click Next then choose DLL for Application type and check Empty Project.

4. In the Solution Explorer, right-click on Header Files and choose Add > Existing Item. Select all of the header files that you need. Do the same for Source Files.

5. Go to Project > Properties, then under Configuration Properties –

   a. General – ensure that you are using the correct Character Set. For me it was Use Multi-Byte Character Set. Python 3 probably needs Use Unicode Character Set.

   b. Debugging – enter the path to Python in the Command field. (e.g. C:\Python27\python.exe). Then set Attach to Yes.

   c. Linker > General – change the Output File to end in .pyd instead of .dll.

6. Ensure that your configuration is set to Debug. Go to Build > Build Solution.

7. Open a cmd and cd into the directory where your pyd file was compiled. Start python from the cmd window. To attach debugger on this running python process, go back to Visual Studio and click the green play button to start debugging. You can also use Debugging -> Attach to Process… Now go back to Python and import your module. Play, test, and try to break it!