[ python-Bugs-1193099 ] Embedded python thread crashes

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Bugs item #1193099, was opened at 2005-04-30 12:03
Message generated for change (Comment added) made by ugodiggi
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: ugodiggi (ugodiggi)
Assigned to: Nobody/Anonymous (nobody)
Summary: Embedded python thread crashes

Initial Comment:
The following code 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). 
I can reproduce the same behavior on another wxp
system, under python 2.4. 

The crash happens (in the python thread) 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. 

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.

Cheers and ciao 

Ugo 

////////////////////////// TestPyThreads.cpp
////////////////////////// 
#include <windows.h> // Sleep
#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; 
} 
 


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>Comment By: ugodiggi (ugodiggi)
Date: 2005-10-05 11:39

Message:
Logged In: YES 
user_id=1269908

I would guess that the problem is going to be windows 
specific?
I tested similar problem on both the debug and release build,
and I did try to get some comment on comp.lang.python
i.e.
http://mail.python.org/pipermail/python-list/2005-
April/278404.html

my comment on the debugging was:
> 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.

I did not look at the python code long enough to follow it.
I will try to reproduce tonight and send out the stack - for 
whatever reason I'm not finding it any longer.


----------------------------------------------------------------------

Comment By: Neal Norwitz (nnorwitz)
Date: 2005-10-03 22:37

Message:
Logged In: YES 
user_id=33168

I can't reproduce on gentoo linux (amd64) with a debug
build.  I played with different values for sleep.  BTW, it
would be better if you attached the code as a file, since
formatting is lost.

Can you try to debug this problem?
Can you attach info from the debugger?

----------------------------------------------------------------------

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