"Mark English" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] Is there a safe way to run tkinter in a multithreaded app where the mainloop runs in a background thread ?
Mark, I tried your code snippet with Python 2.3.4. Worked fine. Only problem was that the program fell off the end and terminated before the second thread could open the Tkinter window. So I added these lines at the end to make the main thread wait:- from msvcrt import kbhit, getch print "\n\nPress key to end" while not kbhit(): pass getch() Both your Hello and Quit buttons worked. However, I have found that tkinter crashes if any components, labels text box etc, are accessed directly from another thread. Below is a posting I did some time ago. My solution to the problem. I'm still interested to know if this is a good/best way to solve this problem. It is not optimal in that 'otherThread' runs continuously even when the label is not being updated. What a waste of cpu cycles! This shows up in that other windows apps slow right down. What is needed is a comms method between threads that causes a thread to block while it's waiting for data rather than my continuous polling approach. Would a Queue help here? John Pote "Martin Franklin" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > On Tue, 09 Nov 2004 17:41:56 GMT, John Pote <[EMAIL PROTECTED]> > wrote: > >> Running my programme in Python 2.3.4 I received the following msg in the >> consol :- >> (Pent III running W2K prof) >> >> """ >> Exception in Tkinter callback >> Traceback (most recent call last): >> File "c:\apps\python\234\lib\lib-tk\Tkinter.py", line 1345, in __call__ >> return self.func(*args) >> File "c:\apps\python\234\lib\lib-tk\Tkinter.py", line 459, in callit >> self.deletecommand(tmp[0]) >> AttributeError: 'str' object has no attribute 'deletecommand' >> UpdateStringProc should not be invoked for type option >> >> abnormal program termination >> """ >> There was no other traceback information. >> >> Could this be related to lines of the ilk:- >> self.infoSpd.config(text="%d.%01d"%spd) >> where infoSpd is a Tkinter Label object placed using the grid manager. >> >> Thousands of these updates were performed so the labels displayed >> progress >> through a memory dump of a system accessed through a serial port. >> >> I had trouble before with Python versions 2.2.1 and 2.2.3 where >> commenting >> out these Label updates stopped the system crashing and it was happy to >> run >> for hours performing tests on the external hardware. (an embedded data >> logger I'm developing) >> >> Anyone any thoughts? >> >> John > > > Only one (thought that is) Are you updating thses Label widgets from > other > threads? and could you possibly post an example? > > Martin Ahhhh -- Experience had already taught me that lesson about tkinter. On checking my code guess what I found I'd done - called the widget.config method from the other thread. So I put in a list to queue the label updates from the other thread to the tkinter thread and it's now been running for several hours without problem. Thanks for the reminder. BTW the program structure I've been using is:- def otherThread(): while TRUE: if updatelabel: labelQ = "new label text" def guiLoop(): if labelQ: myLabel.config(text=labelQ) labelQ = None #re-register this fn to run again rootWin.after(10, guiLoop) #strangely .after_idle(guiLoop) is slower! . . rootWin = Tk(className=" tester") #rest of GUI set up. then:- thread.start_new( otherThread, () ) rootWin.after(50, guiLoop) rootWin.mainloop() It works but is it the best way to do this sort of thing? The point is that I need moderately fast serial comms, which I do in 'otherThread' and found the 'after' and 'after_idle' call backs were too slow. The timing I did on py2.2.1 indicated that 'after_idle' could not do better than ~70ms and 'after(10, ....)' was faster, 30-40 ms, but still too slow for my app. Any more thoughts appreciated. John -- http://mail.python.org/mailman/listinfo/python-list
