[Python-Dev] Threading and callbacks - missing documentation
Fri, 12 Apr 2002 14:21:17 -0400
> ... I believe Mark Hammond has a general set of C++
> classes to help with this stuff on Windows, but IIRC
> they rely on Windows-specific TLS (thread local
> storage) gimmicks.
> No TLS. Mark's stuff actually relies on being
> called (at some point) with the GIL so he can
> grab the interpreter- and thread-states.
Yes TLS, and all over the place. Look at the code for any of
PyWinInterpreterLock_Release, PyWinThreadState_Free, PyWinThreadState_Clear
or DLLMAIN. TLS is used to remember what a thread's PyThreadState is, and
to determine whether a thread already has a PyThreadState (it does iff the
TLS slot at dwTlsIndex is non-NULL). Simple example:
// Asuming we have a valid thread state, acquire the Python lock.
ThreadData *pData = (ThreadData *)TlsGetValue(dwTlsIndex);
PyThreadState *thisThreadState = pData->ts;