[Python-Dev] Preventing PyEval_AcquireLock deadlock

[Guido van Rossum]

> Is there an easy way in the API to check if the current thread already has
> the interpreter lock so I can avoid calling PyEval_AcquireLock again?  If
> so, is it available all the way back to 1.5.2?

I don't think so.  It's easy to check whether *some* thread has the
lock, but the lock abstraction doesn't have a notion of ownership by a
specific thread.

Let's take a step back.  Why do you need this?  I'm guessing that you
have a C++ library that calls C++ callbacks, and now you want to call
a Python callback from your C++ callback.  The proper solution is to
make sure that you *always* release the Python lock before entering
your event loop or anything else that could possibly call callbacks.
See _tkinter for how I handled it there.  It's ugly, but possible.

--Guido van Rossum (home page: http://www.python.org/~guido/)