[Python-Dev] Problem with embedded python - bug?

28 Apr 2005

      I have been having a few more discussions around about this, and I'm starting to think that this is a bug.

My take is that, when I call Py_Finalize, the python thread should be shut down  gracefully, closing the file and everything. 
Maybe I'm missing a call to something (?PyEval_FinalizeThreads?) but the docs seem to say that just PyFinalize should be called.

The open file seems to be the issue, since if I remove all the references to the file I cannot get the program to crash.

I can reproduce the same behavior on two different wxp systems, under python 2.4 and 2.4.1.

Ugo

-----Original Message-----
From: Ugo Di Girolamo 
Sent: Tuesday, April 26, 2005 2:16 PM
To: 'python-dev@python.org'
Subject: Problem with embedded python

I have the following code, that seems to make sense to me. 

However, it crashes about 1/3 of the times. 

My platform is Python 2.4.1 on WXP (I tried the release version from 
the msi and the debug version built by me, both downloaded today to 
have the latest version). 

The crash happens while the main thread is in Py_Finalize. 
I traced the crash to _Py_ForgetReference(op) in object.c at line 1847, 
where I have op->_ob_prev == NULL.

What am I doing wrong? I'm definitely not too sure about the way I'm 
handling the GIL. 

Thanks in adv for any suggestion/ comment

Cheers and ciao 

Ugo 

////////////////////////// TestPyThreads.py ////////////////////////// 
#include  
#include "Python.h" 

int main() 
{ 
        PyEval_InitThreads(); 
        Py_Initialize(); 
        PyGILState_STATE main_restore_state = PyGILState_UNLOCKED; 
        PyGILState_Release(main_restore_state); 

        // start the thread 
        { 
                PyGILState_STATE state = PyGILState_Ensure(); 
                int trash = PyRun_SimpleString( 
                                "import thread\n" 
                                "import time\n" 
                                "def foo():\n" 
                                "  f = open('pippo.out', 'w', 0)\n" 
                                "  i = 0;\n" 
                                "  while 1:\n" 
                                "    f.write('%d\\n'%i)\n" 
                                "    time.sleep(0.01)\n" 
                                "    i += 1\n" 
                                "t = thread.start_new_thread(foo, ())\n" 
                                ); 
                PyGILState_Release(state); 
        } 

        // wait 300 ms 
        Sleep(300); 

        PyGILState_Ensure(); 
        Py_Finalize(); 
        return 0; 

}