[C-API] Weird sys.exc_info reference segfault

Jonas H. jonas at lophus.org
Sun Oct 3 16:33:48 CEST 2010

On 10/03/2010 03:47 PM, Antoine Pitrou wrote:
> You shouldn't call PyObject_FREE yourself, but instead rely on
> Py_DECREF to deallocate it if the reference count drops to zero.
> So, instead of commenting out Py_DECREF and keeping PyObject_FREE, I'd
> recommend doing the reverse. That way, if a reference is still living
> in the frame, the object doesn't get deallocated too early.

Humm. Now the behaviour is as follows:

with assignment to local variable
* start_response = PyObject_NEW(...) -> start_response->ob_refcnt=1
* wsgiapp(environ, start_response)   ->                 ob_refcnt=2
* Py_DECREF(start_response)          ->                 ob_refcnt=1

without assignment
* start_response = PyObject_NEW(...) -> start_respinse->ob_refcnt=1
* wsgiapp(environ, start_response)   ->                 ob_refcnt=1
* Py_DECREF(start_response): CRASH

I think I'll compile Python with debug support to check out what's going 
wrong in the second case.


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