[Matplotlib-users] Matplotlib, Tk, and multithreading

[Oliver K. <oli...@gm...>]

Hi,

I have a library which uses matplotlib to produce some plots. This library is called by a thread. However, python crashes with this error when it tries to plot something:

Tk_MacOSXSetupTkNotifier: first [load] of TkAqua has to occur in the main thread!

If I do as it says and call "window = Tkinter.Tk()" in the main thread before spawning the thread which calls the plotting routines, it works well until the program shuts down. When shutting down, I get a series of these messages (8 of them, to be precise):

Exception RuntimeError: RuntimeError('main thread is not in main loop',) in <bound method PhotoImage.__del__ of <Tkinter.PhotoImage instance at 0x90fe260>> ignored

Googling reveals to me that this is a problem with Tk: it doesn't like threading. I tried to force matplotlib to use a different backend with this command:
matplotlib.rcParams['backend'] = something_else
but it still crashes with the first error.

Has anyone encountered this problem before? How did you overcome it?

Cheers,
Oliver