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How to easily avoid Tkinter freezing?

I developed a simple Python application doing some stuff, then I decided to add a simple GUI using Tkinter.
The problem is that, while the main function is doing its stuff, the window freezes.
I know it's a common problem and I've already read that I should use multithreads (very complicated, because the function updates the GUI too) or divide my code in different function, each one working for a little time.
Anyway I don't want to change my code for such a stupid application.
My question is: is it possible there's no easy way to update my Tkinter window every second? I just want to apply the KISS rule!
I'll give you a pseudo code example below that I tried but didn't work:
class Gui:
[...]#costructor and other stuff
def refresh(self):
self.root.update()
self.root.after(1000,self.refresh)
def start(self):
self.refresh()
doingALotOfStuff()
#outside
GUI = Gui(Tk())
GUI.mainloop()
It simply will execute refresh only once, and I cannot understand why.
Thanks a lot for your help.

Tkinter is in a mainloop. Which basically means it's constantly refreshing the window, waiting for buttons to be clicked, words to be typed, running callbacks, etc. When you run some code on the same thread that mainloop is on, then nothing else is going to perform on the mainloop until that section of code is done. A very simple workaround is spawning a long running process onto a separate thread. This will still be able to communicate with Tkinter and update it's GUI (for the most part).
Here's a simple example that doesn't drastically modify your psuedo code:
import threading
class Gui:
[...]#costructor and other stuff
def refresh(self):
self.root.update()
self.root.after(1000,self.refresh)
def start(self):
self.refresh()
threading.Thread(target=doingALotOfStuff).start()
#outside
GUI = Gui(Tk())
GUI.mainloop()
This answer goes into some detail on mainloop and how it blocks your code.
Here's another approach that goes over starting the GUI on it's own thread and then running different code after.

'Not responding' problem can be avoided using Multithreading in python using the thread module.
If you've defined any function, say combine() due to which the Tkinter window is freezing, then make another function to start combine() in background as shown below:
import threading
def combine():
...
def start_combine_in_bg():
threading.Thread(target=combine).start()
Now instead of calling combine(), you have to call start_combine_in_bg()
I did this and now my window is not freezing so I shared it here. Remember you can run only one thread at a time.
Have a look for reference: stackoverflow - avoid freezing of tkinter window using one line multithreading code

Here's how I managed to work around this issue (maybe it's quite dirty I don't know):
Whenever I update my tkinter window through the doingALotOfStuff() function, I call myTk.update().
It avoids freezing for me.

PyGObject (Glade) Window Never Showing (Multithreaded)

I've been fighting for three hours now to get this process multithreaded, so that I can display a progress box. I finally got it working, insomuch as the process completes as expected, and all the functions call, including the ones to update the progress indicator on the window.
However, the window never actually displays. This is a PyGObject interface designed in Glade. I am not having fun.
def runCompile(obj):
compileWindow = builder.get_object("compilingWindow")
compileWindow.show_all()
pool = ThreadPool(processes=1)
async_result = pool.apply_async(compileStrings, ())
output = async_result.get()
#output = compileStrings() #THIS IS OLD
compileWindow.hide()
return output
As I mentioned, everything works well, except for the fact that the window doesn't appear. Even if I eliminate the compileWindow.hide() command, the window never shows until the process is done. In fact, the whole stupid program freezes until the process is done.
I'm at the end of my rope. Help?
(By the way, the "recommended" processes of using generators doesn't work, as I HAVE to have a return from the "long process".)

I'm not a pyGobject expert and i don't really understand your code. I think that you should post more. Why are you calling the builder in a function? you can call it at the init of the GUI?
Anyways.. It seems that you are having the common multithread problems..
are you using at the startup GObject.threads_init() and Gdk.threads_init() ?
Then, if you want to show a window from a thread you need to use Gdk.threads_enter() and Gdk.threads_leave().
here is an useful doc

I changed the overall flow of my project, so that may affect it. However, it is imperative that Gtk be given a chance to go through its own main loop, by way of...
if Gtk.events_pending():
Gtk.main_iteration()
In this instance, I only want to call it once, to ensure the program doesn't hang.
(The entire program source code can be found on SourceForge. The function in question is on line 372 as of this posting, in function compileModel().

Obscure, repeatable crashes in multi-threaded Python console application using tk

Using tk in my multi-threaded(*) console application causes it to crash without stacktrace, giving the message "Tcl_WaitForEvent: Notifier not initialized Abort trap".
The symptoms were that all my program's functions worked fine, until I brought up the tk window - then the very next operation would cause the crash.
Immediate searching found that Tkinter is not safe with respect to Python threads, so I made sure that I was not calling any Tk functions anywhere other than my main thread. The crashes continued.
I lost several hours because I believed that it was the specific command I was using that crashed the program - but eventually I realized that any keyboard input would crash the program.
After a lot of debugging, I finally boiled it down to a small program that demonstrates the issue, exposing what I believe is a bug or certainly a feature that needs documentation in the Tkinter library.
I was working on this posting I was debugging. I'm going to post it and answer my own question in the hopes that it will prevent the next person from wasting a day on it.
--
(* - Yes, it certainly needs to be multi-threaded. I have a thread for my socket connection, a thread that listens to a mic and finds levels, a thread to drive my serial port and more. In each case, the thing I'm reading on the thread naturally blocks most of the time.)

The solution!
The issue is that tk crashes if you read from Python's raw_input in a different thread from the tk thread!
A small program demonstrating the issue is here. If you run it, it gets keyboard input perfectly happily from the second thread - until you enter the command "tk" when it brings up an empty tk window. You can do whatever you like with that window - until you type in the console window and press return, when the whole program crashes.
Why am I reading from raw_input in a thread that isn't the main thread?
My program is a console application, but I'm controlling a lot of different parts, one of which is the pi3d OpenGL ES 2.0 graphics library which must be updated at or near the frame rate from the main Python thread.
How to work around it?
"Simple" enough - register for tk menu events and just get the keys directly! Except that's a crappy solution, because you have to emulate all those things that the console does for you already - deleting, left and right arrows and that sort of thing. But that's what I'll have to do.
Should the program become a fully-fledged tk application?
But I can't do that - the whole point of this program is that you can run it through a terminal window - often sshing into headless machines. I'm frankly more likely to make it a curses program!
The tk window is a minor part of the whole thing - just a window to show emulated lights when developing if you don't have the hardware hooked up (or don't want to keep flashing yourself in the face). I won't try to bring it up on headless machines, and that's fine.
Is this a bug?
I'm always loathe to attach such a label to software not my own, but I'm hard-pressed to come up with any other description. It causes a crash, and that crash produces no useful information of any type. I consider that Tkinter is somewhat lame for simply crashing when called from different threads, but at least this behavior is documented (if you dig down a little) - in this case, I'm calling a Python built-in, so I have no basis to expect that it will interact with this library at all, and there's no documentation of this problem.
Could there be a workaround?
I'm sort of hoping there will be a work-around - this one-page program was a single item on a long list of features has turned into a full-day head-scratching debugging session and I don't want to have to throw another day at least after this when none of this time is actually producing new features.
The best thing is if the tk team admitted this was a bug and came up with a fix. But I wouldn't expect that at my desktop before a year from now...
So perhaps the real best thing would be if there were some way to get tk to simply ignore the keyboard, and not crash. I did a tiny experiment with tk's "busy" but that didn't work and just doesn't seem to be the right sort of thing.
A little later, I'm now thinking about running the lighting as an independent program, a separate subprocess using Python's Subprocess library, and sending it text commands through stdin. This would be overkill if this were the only problem that was being solved, but in fact
Got it.
Replacing raw_input() with sys.stdin.readline() did the trick - at least in the demo (which I updated). Feel free to download this and experiment with it yourself!
I hope this saves someone else the time.

In my case (as mentioned in the comments under #Tom Swirly's answer) the solution was to switch to a non-interactive backend:
import matplotlib
matplotlib.use('Agg')

mtTkinter doesn't terminate threads

I need to run some simple function in multi-threading with a Tkinter GUI, so I've tried mtTkinter.
Everything works fine except for a particular: even if I just start the GUI and then I close it without touching nothing some thread keeps running.
In other words; I have this code:
from Tkinter import *
root = Tk()
#simple GUI code with buttons, labels, text and scrollbars widget
...
...
root.mainloop()
If I run this code the GUI appears and when I close it this python script ends successfully.
Now if I replace Tkinter with mtTkinter
from mtTkinter import *
root = Tk()
#simple GUI code with buttons, labels, text and scrollbars widget
...
...
root.mainloop()
the GUI appears once again, but if I close it there is still some thread from mtTkinter that keeps running!
Any help would be apprecied, thank you in advance and sorry for my bad english!

I ran into a similar problem for my application (https://github.com/joecole889/spam-filter). After some investigation, I realized that when I close my application Tkinter (or possibly Matplotlib) uses a threading._DummyThread instance to delete one of the widgets. I have a Matplotlib graph in a Tkinter canvas widget in my application. In any case, it looks like an “image delete” event is added to the event queue and mtTkinter blocks waiting for a response on the responseQueue that never comes.
I was able to fix the problem by allowing events from instances of threading._DummyThread to run without going through the queue infrastructure of mtTkinter. That is, I changed:
if threading.currentThread() == self._tk._creationThread:
to
if (threading.currentThread() == self._tk._creationThread) or \
isinstance(threading.currentThread(), threading._DummyThread) :
Things seem to be working for me now...hope this helps!

I've "resolved" not using it. mTkinter seems to be a bit buggy.

This is an old topic, but I don't see where it was even closed. I have a python application using 4 threads using the 'theading' module and MtTkinter.
I was having similar problems with MtTkinter. The application worked but would not close. I have searched and tried quite a few solutions, none worked. For my application, using queues would have been a chore.
Here is what I did. Its not elegant, but it worked. Its pretty ruthless.
cleanup():`
pidx = os.getpid()
cmd1 = "kill" + " " + str(pidx)
if __name__ == "__main__":
os.system(cmd1)

Tkinter doesn't play nicely with multiprocessing

The following code hangs without doing anything in Python 3.2.2 in Linux:
import tkinter
from multiprocessing import Process
def f():
root = tkinter.Tk()
label = tkinter.Label(root)
label.pack()
root.mainloop()
p = Process(target=f)
p.start()
The only information I have found about this problem is issue 5527, in which it is noted that the problem is with tkinter being imported before the process is forked, and that it can be fixed by importing tkinter inside the function f, and that the problem occurs in Linux but not Solaris.
What exactly is causing this problem, and is it a bug? Is there any workaround other than to import tkinter locally everywhere I need it (which isn't very Pythonic)? Do any other modules have similar issues with multiprocessing?

My suspicion is that the problem has to do with the connection to the X server (usually a socket). If this is created before the process is fork()-ed, the child process inherits this connection. But if it tries to use it, the X server gets confused.
After a cursory look at at Tkinter.py, it looks like maybe calling the NoDefaultRoot function before starting the process might be useful. It all depends on when the connection to the X server is made.
Otherwise importing Tkinter after the fork seems the way to go.

As of September 2013, there are some additional comments on the bug report that give more insight into what the actual problem is.
http://bugs.python.org/issue5527#msg194848
http://bugs.python.org/issue5527#msg195480
Based on the above, I'm guessing something like the following is happening: Tkinter is not thread safe, so (for whatever reason) Tkinter wants to know which thread is the main thread. Tkinter assumes that the main thread when the Tkinter module is loaded will also be the main thread for program execution. When you fork or multiprocess after loading Tkinter, this assumption is broken. (For example, after a fork, the remembered main thread is in the parent, not the child.)

If you can get a thread started, just do root.mainloop() after it and it should work fine.