Hi all, I'm working on embedding Python in a multi threaded application but found mostly old or confusing info on this. Can anyone point me to the right direction or send some working examples? Detail: Python 2.5.1, MacOSX Leopard 10.5.1, using Pytohn/C API The application initializes Python in a shared library, which in turn links in more libraries that may or may not use C API commands in parallel. Generally it all works fine, but when two libraries try to access Python code I get seg fault or similar. The closest I got to resolve this is based on this message: http://groups.google.fi/group/comp.lang.python/msg/fe4e114d1e1a741d which suggests starting a new sub interpreter for each task. However, i still get errors like below. (Thread 0 on it's own works fine.) According to the docs PyObject_HasAttrString should always succeeds so I don't understand what happens. Also I get thread mix-up messages randomly even though I double checked the implementation. 2 Threads accessing Python: ------------------------------- Thread 0 Crashed: 0 org.python.python 0x15a58bcc PyErr_Occurred + 16 (errors.c:77) 1 org.python.python 0x159c642c instance_getattr + 277 (classobject.c:698) 2 org.python.python 0x159f789b PyObject_HasAttrString + 116 (object.c:1069) While Thread 4 is running a process: ---------------------------------------- Thread 4: 0 org.python.python 0x15a43751 PyEval_EvalFrameEx + 794 (ceval.c:852) 1 org.python.python 0x15a49cdc PyEval_EvalCodeEx + 1819 (ceval.c:2831) 2 org.python.python 0x159df537 function_call + 320 (funcobject.c:517) 3 org.python.python 0x159be278 PyObject_Call + 45 (abstract.c:1860) 4 org.python.python 0x159c5ee5 instancemethod_call + 401 (classobject.c:2497) 5 org.python.python 0x159c297c PyObject_CallMethodObjArgs + 223 (abstract.c:1860) Thanks for any advice, George