[Python-Dev] Bug? is Tkinter+no threads+Windows supported?

[montanaro@tttech.com]

My client is trying to build a version of Python on Windows with Tkinter and
pymalloc enabled, and threads disabled (in part because pymalloc is not
thread-safe).  There appears to be a bug in _tkinter.c:EventHook.  It has
this code:

    #if defined(WITH_THREAD) || defined(MS_WINDOWS)
                    Py_BEGIN_ALLOW_THREADS
                    PyThread_acquire_lock(tcl_lock, 1);
                    tcl_tstate = event_tstate;

                    result = Tcl_DoOneEvent(TCL_DONT_WAIT);

                    tcl_tstate = NULL;
                    PyThread_release_lock(tcl_lock);
                    if (result == 0)
                            Sleep(20);
                    Py_END_ALLOW_THREADS
    #else
                    result = Tcl_DoOneEvent(0);
    #endif

It seems on the surface that the "|| defined(MS_WINDOWS)" bit should be
deleted.  This code dates from 1998 and comes with this log text:

    revision 1.72
    date: 1998/06/13 13:56:28;  author: guido;  state: Exp;  lines: +26 -6
    Fixed the EventHook() code so that it also works on Windows, sort of.
    (The "sort of" is because it uses kbhit() to detect that the user
    starts typing, and then no events are processed until they hit
    return.)

    Also fixed a nasty locking bug: EventHook() is called without the Tcl
    lock set, so it can't use the ENTER_PYTHON and LEAVE_PYTHON macros,
    which manipulate both the Python and the Tcl lock.  I now only acquire
    and release the Python lock.

    (Haven't tested this on Unix yet...)

This suggests that Guido was (rightly) worried about the case of threading
on Windows.  What about a non-threaded interpreter on Windows?

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