How to savely end a python sub-interpreter from a different thread?

[Gernot Hillier]

Hi!

I'm developing a communication application which uses python as embedded 
script language. The python controls the work which is done when the 
connection is established. So when I receive a connection request, a new 
thread containing a new python sub-interpreter is created. 

Now I have the problem that the connection can be ended at any time from the 
other side. I get a notification about this in another thread.

Now my problem is: how to end the python script gracefully at this moment?

Currently I've introduced a new Exception in my python extension. I then 
throw this exception from the other thread into the right python 
interpreter. So the script will (hopefully) get it and can end gracefully.

Here's some code of the other thread:

void Connection::ConnectionLost()  
{
[...]
        if (py_state) {
                // acquire lock, switch to right thread context
                PyEval_RestoreThread(py_state); 
                PyErr_SetString(CallGoneError,"Call was finished from partner.");
                PyEval_SaveThread();
        }
[...]
}

py_state is set to the PyThreadState* of the running Python interpreter.

This works most times, but sometimes it seems to cause some problems leading 
to crashes in Py_EndInterpreter() for the current connection or the 
subsequent Py_NewInterpreter()  for the next connection. These problems 
especially seem to occur when two Python sub-interpreters are deleted 
nearly at the same time. 

As I suspected stack corruption, I tried to LD_PRELOAD libefence.so. Now I 
get the following back trace:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1026 (LWP 12720)]
0x080ce3e3 in PyErr_SetObject (exception=0x432a8fe0, value=0x42152fc8) at 
Python/errors.c:55
55              Py_XINCREF(exception);
Current language:  auto; currently c
(gdb) bt
#0  0x080ce3e3 in PyErr_SetObject (exception=0x432a8fe0, value=0x42152fc8) 
at Python/errors.c:55
#1  0x080ce4ae in PyErr_SetString (exception=0x432a8fe0, string=0x8103420 
"Connection was finished from partner.") at Python/errors.c:70
#2  0x0805d96d in Connection::ConnectionLost() () at connection.cpp:351

Can someone tell me what's the problem here?

Or has someone any better idea what to do to end the python interpreter?

TIA!!

-- 
Ciao,

Gernot