deets at nospam
Jul 7, 2009, 6:23 AM
Post #2 of 3
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Re: Tkinter.Canvas thread safety problem?
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Zdenek Maxa wrote:
> Hello,
>
> I have started a project using Tkinter. The application performs some
> regular checks in a thread and updates Canvas components. I have
> observed that sometimes the application hangs when it is about to call
> canvas.itemconfig() when the thread is about to terminate in the next
> loop.
>
> Experimenting with this problem for a while, I have compiled a little
> example which always reproduces the problem. Commenting out the line 52
> (before canvas.itemconfig()), the example always finishes all right,
> having the delay there, it hangs.
>
> I would like to ask if you could have a look at the snippet in the
> attachment and tell me if that is actually me doing something wrong or
> indeed Tkinter thread safety problem and what the workaround could be.
>
> Could you please also comment on wxPython thread safety?
>
As a rule of thumb, GUI-toolkits aren't threadsafe. Qt being a notable
exception to this rule.
There are various ways to cope with this, mostly through injecting events
into the event-queue of the main gui thread, or using timers.
This is also true for wx (google wx python threading for a plethora of
information on this)
For Tx, I dimly remember an "after" function that can be used to invoke
timer-based code. Use that to update aggregated data from the events.
Diez
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tkinter_thread_safety.py
