The c extend module is as the attached file "WindowsFuncs.cpp", it 
wraps some Windows event APIs

The python script is as the attached file "test.py", run that script, 
we could find in the new thread, the calling to Windows API 
waitForSingleObject will block the main thread printing, that's really 
strange. 

The output of running is as the attached file "test.output".

You have to release the GIL. See http://docs.python.org/api/threads.html
for some information.

Yes, after wrapping the calling to block operation with marco 
Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS, that issue is gone. 
Thank you.