mtTkinter - A thread-safe version of Tkinter
Although Tkinter is technically thread-safe (assuming Tk is built with --enable-threads), practically speaking there are still problems when used in multithreaded Python applications. The problems stem from the fact that the _tkinter module attempts to gain control of the main thread via a polling technique when processing calls from other threads. If it succeeds, all is well. If it fails (i.e., after a timeout), the application receives an exception with the message: "RuntimeError: main thread is not in main loop". There is no way to tell when this might happen, so calling Tk routines from multiple threads seems to be problematic at best.
The mtTkinter module solves this problem by modifying some Tkinter module definitions (in memory). The modified code intercepts out-of-thread Tkinter calls and marshals them through a queue which is read by an 'after' event running periodically in the main loop. This is similar to the technique used in many other platforms (e.g., .NET's InvokeRequired/Invoke mechanism). The technique used in mtTkinter is exception-safe as well, marshaling exceptions through a response queue back to the caller's thread.
Note that, because it modifies the original Tkinter module in memory, other modules that use Tkinter (e.g., Pmw) reap the benefits automagically as long as mtTkinter is imported at some point before additional threads are created.
import mtTkinter as Tkinter
from mtTkinter import *
Get it here: mtTkinter-0.4.tar.gz. Enjoy!
License: Released under LGPL from version 0.4.
Author: Allen B. Taylor, a dot b dot taylor at gmail dot com