I've successfully embedded Python for a single thread I tried to extend the implementation for multiple threads (a worker thread scenario) and I'm encountering either deadlocks or seg faults depending upon how I got about it. There seems to be some inconsistency between what is covered in the docs here: http://docs.python.org/2/c-api/init.html#non-python-created-threads and the experiences of other users trying the same thing, e.g. http://bugs.python.org/issue19576 http://wiki.blender.org/index.php/Dev:2.4/Source/Python/API/Threads Can anybody comment on the situation, in particular, Is the non-python-created-threads documentation accurate for v2.7? If a main thread does things like importing a module and obtaining a reference to a Python method, can those things be used by other C++ threads or do they have to repeat those lookups? Is there any logic that needs to be executed once only as each thread is started? (the doc suggests just PyGILState_Ensure/PyGILState_Release each time a thread accesses Python methods - is there anything else?) Given the bug 19576, what is the most portable way to code this to work reliably on unfixed Python versions? (e.g. should users always explicitly call PyEval_InitThreads() in their main thread or worker threads or both?) Here is my actual source code: https://svn.resiprocate.org/viewsvn/resiprocate/main/repro/plugins/pyroute/ (see example.py for a trivial example of what it does) The problem that I encounter: - the init stuff runs fine in PyRoutePlugin.cxx, it calls Py_Initialize, PyEval_InitThreads, PyImport_ImportModule and looks up the "provide_route" method in the module it creates a PyRouteWorker object, giving it a reference to "provide_route" it creates a thread pool to run the worker - the PyRouteWorker::process() method is invoked in one of those threads - it crashes when trying to call the "provide_route" method PyRouteWorker.cxx: routes = mAction.apply(args); Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7ffff30b8700 (LWP 23965)] 0x00007ffff3d6ad06 in PyObject_Call () from /usr/lib/libpython2.7.so.1.0 (gdb) bt #0 0x00007ffff3d6ad06 in PyObject_Call () from /usr/lib/libpython2.7.so.1.0 #1 0x00007ffff3d6b647 in PyEval_CallObjectWithKeywords () from /usr/lib/libpython2.7.so.1.0 #2 0x00007ffff414885a in apply (args=..., this=<optimized out>) at /usr/include/python2.7/CXX/Python2/Objects.hxx:3215 #3 repro::PyRouteWorker::process (this=0x6f00a0, msg=<optimized out>) at PyRouteWorker.cxx:98 #4 0x00007ffff7b879e1 in repro::WorkerThread::thread (this=0x68e110) at WorkerThread.cxx:36 #5 0x00007ffff70b7a2f in threadIfThreadWrapper (threadParm=<optimized out>) at ThreadIf.cxx:51 #6 0x00007ffff65ffb50 in start_thread (arg=<optimized out>) at pthread_create.c:304 #7 0x00007ffff5999a7d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112 #8 0x0000000000000000 in ?? ()