[Python-Dev] Threading and callbacks - missing documentation (original) (raw)

Jack Jansen Jack.Jansen@oratrix.com
Fri, 12 Apr 2002 23:59:20 +0200

Well, as PY_BEGIN_ALLOW_THREADS and PY_END_ALLOW_THREADS currently work, should we really try to fix them with TLS?

What I would like to see, though, is a way to get at the thread state iff the current platform has thread local storage.

My direct problem (the MacPython/MachoPython one, the work problem is different) is that various MacOS API calls such as WaitNextEvent() can cause callbacks to be called (in the current thread). And as these calls block I'd like to bracket them with PY_BAT/PY_EAT. But I know that in both MacPython and MachoPython I have pthreads, and thus TLS, and thus I can count on using it in the callback routine.

Moreover, using the TLS only for callback routines allows me to go one further. If other packages that I use (Tk, for instance) call WaitNextEvent while holding the interpreter lock it could cause on of "my" callbacks to be called. But if we have both the TLS and the old mechanism we can detect the situation that the callback is called from the thread holding the interpreter lock and we can compensate for it.