With threaded Tkinter, TkinterHanders3.py from https://bugs.python.org/issue33257 (attached) hangs.
Tracing with thread_debug and a modified trace.py (to show TIDs, attached) shows that worker threads are waiting for the Tcl lock while the main thread that holds it keeps waiting for some other lock with a strange timeout:
19000: PyThread_acquire_lock_timed(00000000001B0F80, 0) called
19000: PyThread_acquire_lock(00000000001B0F80, 0) -> 0
19000: PyThread_acquire_lock_timed(00000000001B0F80, -1000000) called
Tested on 3.6 head, win7 x64, debug build. |