[C++-sig] Extending python and using debug interpreter on Linux

[Brian O'Kennedy]

After diving deeper into boost.python and python than I felt comfortable
with, I found my own stupid mistake. 

On Windows, the presence of _DEBUG causes Py_DEBUG to be defined, but
this is not the case on Linux. When I include boost/python.hpp I need to
define both BOOST_DEBUG_PYTHON and Py_DEBUG: Currently I'm wrapping
includes of boost.python like so:

-------------------------------------------------------------
#define BOOST_PYTHON_NO_LIB

#ifdef _DEBUG
  #define BOOST_DEBUG_PYTHON
  #ifndef WIN32 
    #define Py_DEBUG
  #endif
  #pragma comment(lib, "boost_python-vc80-mt-gyd-1_38.lib" )
#else
  #pragma comment(lib, "boost_python-vc80-mt-1_38.lib" )
#endif

#include <boost/python.hpp>
-------------------------------------------------------------


-----Original Message-----
From: cplusplus-sig-bounces+brian.okennedy=vicon.com at python.org
[mailto:cplusplus-sig-bounces+brian.okennedy=vicon.com at python.org] On
Behalf Of Brian O'Kennedy
Sent: 21 April 2009 16:12
To: Cplusplus-sig at python.org
Subject: [C++-sig] Extending python and using debug interpreter on Linux

Hi, 

I've built a local copy of Python with PY_DEBUG enabled and tried import
a simple module which only defs a single c++ function returning a
std::string.  My test involves importing the module, and then quitting
the interpreter; I'm not trying to call anything in the module. 

This works as expected in Release mode on linux (as well as working
correctly on Windows for Release and Debug(with PY_DEBUG).  

However, on Linux using the debug interpreter I get a "Fatal Python
error: UNREF invalid object" with the callstack as follows:

#0  0xb7f3e430 in __kernel_vsyscall ()
#1  0xb7bf48a0 in raise () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7bf6268 in abort () from /lib/tls/i686/cmov/libc.so.6
#3  0xb7ea2837 in Py_FatalError (msg=0xb7ed7ed4 "UNREF invalid object")
at Python/pythonrun.c:1561
#4  0xb7dfe3d2 in _Py_ForgetReference (op=0xb7b87754) at
Objects/object.c:1918
#5  0xb7dfe431 in _Py_Dealloc (op=0xb7b87754) at Objects/object.c:1937
#6  0xb7df2b12 in insertdict (mp=0xb7b89714, key=0xb7b7a208,
hash=1901421549,   value=0xb7efa8a8) at Objects/dictobject.c:420
#7  0xb7df33e0 in PyDict_SetItem (op=0xb7b89714, key=0xb7b7a208,
value=0xb7efa8a8) at Objects/dictobject.c:645
#8  0xb7e8f4b7 in PyImport_Cleanup () at Python/import.c:475
#9  0xb7e9f44c in Py_Finalize () at Python/pythonrun.c:399
#10 0xb7ea2a1e in Py_Exit (sts=0) at Python/pythonrun.c:1618
#11 0xb7ea0e0a in handle_system_exit () at Python/pythonrun.c:1054
#12 0xb7ea0e3b in PyErr_PrintEx (set_sys_last_vars=1)   at
Python/pythonrun.c:1064
#13 0xb7ea0af1 in PyErr_Print () at Python/pythonrun.c:978
#14 0xb7ea00ca in PyRun_InteractiveOneFlags (fp=0xb7d23420,
filename=0xb7eeaf07 "<stdin>", flags=0xbf83f4ac) at
Python/pythonrun.c:795
#15 0xb7e9fcda in PyRun_InteractiveLoopFlags (fp=0xb7d23420,
filename=0xb7eeaf07 "<stdin>", flags=0xbf83f4ac) at
Python/pythonrun.c:723
#16 0xb7e9fb06 in PyRun_AnyFileExFlags (fp=0xb7d23420,
filename=0xb7eeaf07 "<stdin>", closeit=0, flags=0xbf83f4ac)   at
Python/pythonrun.c:692
#17 0xb7eb0ade in Py_Main (argc=1, argv=0xbf83f5b4) at
Modules/main.c:532
#18 0x080485e2 in main (argc=Cannot access memory at address 0x3392

Anyone have any ideas what is going wrong?  I'm aware that there are
issues with Boost Python and Py_Finalize, but is that what is causing
this problem? 

Using Boost 1.38.0 and Python 2.5.4, both built from source on both
Linux Ubuntu gcc42 and Windows Vista using VS2005. 

Thanks, 
 Brian




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