Python crashes when closing figures using TkAgg on Mac OS

Bug report

Bug summary

Python crashes when I create and then close figures in a for loop using the TkAgg backend on Mac OS X in an interactive session. The Python session crashes out with

called Tcl_FindHashEntry on deleted table
Abort trap: 6

This may be related to #7743 and #8387.

Code for reproduction

import sys
import matplotlib as mpl
import pylab as plt

print('OS: %s'%sys.platform)
print('matplotlib version: %s'%mpl.__version__)
print('Backend: %s'%matplotlib.get_backend())

for i in range(3):
    plt.figure()
    plt.close()

plt.figure()
plt.plot([0,1],[0,1])
plt.show()

Actual outcome

$ python -i figure_close.py
OS: darwin
matplotlib version: 2.0.2
Backend: TkAgg
called Tcl_FindHashEntry on deleted table
Abort trap: 6

Expected outcome

I would expect this code to create and destroy three figures before creating and retaining the last figure.

Matplotlib version

Operating system: Mac OS X 10.12.1
Matplotlib version: 2.0.2
Matplotlib backend (print(matplotlib.get_backend())): TkAgg
Python version: 2.7.13

This was matplotlib installed from conda from the conda-forge channel.

I get slightly different (and less fatal) errors with masterish on linux:

18:44 $ python /tmp/tk_close.py 
OS: linux
matplotlib version: 2.1.0.post289+g88a20b7e6
Backend: TkAgg
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"

My guess is that we are creating an tearing down Tk objects when the figures are created and then destroyed, but are leaving things in a limbo-like state. When we finally let the tk event loop run with show() it dies.

@tacaswell

I get the same as @tacaswell on master-ish:

OS: darwin
matplotlib version: 2.1.0.post954+g1d4160c4b
Backend: TkAgg
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"

This unsightly, but it doesn't "crash" python on macOS. Tempted to close this, but I am going to remove the OS/Apple label because the behaviour is the same in MacOS and linux (at least on master).

We should leave this open, there is a real race condition here. Frequently these sorts of things are responsible for more than one odd behavior (that are hard to reproduce due to the race), having a more-or-less reproducible repro example is helpful!

I have seen similar warnings (i.e. can't invoke "event" command: ...) in other situations with version 2.0.2, but they do not appear for me with this simple working example.

Does #9275 help?

This reproduces in PyPy (with PR #9275 and PR #9356 ) as well.

Let me know if I am being too noisy, I am diving into this and using this issue as a record of my work.

Adding some print statements, it seems the problem is starting the event loop after closing the images

first the diff:

diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
index 7a36dc6..6e23b96 100644
--- a/lib/matplotlib/backends/backend_tkagg.py
+++ b/lib/matplotlib/backends/backend_tkagg.py
@@ -214,6 +214,10 @@ class FigureCanvasTkAgg(FigureCanvasAgg):
         self._master = master
         self._tkcanvas.focus_set()
 
+    def close_event(self, *args, **kwargs):
+        print('in close_event')
+        FigureCanvasAgg.close_event(self, *args, **kwargs)
+
     def resize(self, event):
         width, height = event.width, event.height
         if self._resize_callback is not None:
@@ -1079,4 +1083,6 @@ class _BackendTkAgg(_Backend):
 
     @staticmethod
     def mainloop():
+        print('starting main loop')
         Tk.mainloop()
+        print('stopping main loop')

which now prints:

OS: linux2
matplotlib version: 2.1.0+989.g1712678
Backend: TkAgg
in close_event
in close_event
in close_event
starting main loop
can't invoke "event" command: application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
can't invoke "event" command: application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
in close_event
stopping main loop

Note that the errors are after "starting main loop", in other words only after using pylab.show()

or perhaps pyplot.close() is not "doing enough" to remove pending events

PR #9956 fixes the issue for me (linux, PyPy). Could someone on macOS check that it solves the issue for them as well?

@mattip

@mattip Don't worry about being too noisy!

Closed by #9956.
I verified this on OSX.

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Python crashes when closing figures using TkAgg on Mac OS #9856

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Python crashes when closing figures using TkAgg on Mac OS #9856

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tacaswell commented on Nov 25, 2017

jklymak commented on Dec 2, 2017

tacaswell commented on Dec 3, 2017

kadrlica commented on Dec 3, 2017

anntzer commented on Dec 3, 2017

mattip commented on Dec 8, 2017

mattip commented on Dec 8, 2017

mattip commented on Dec 8, 2017

mattip commented on Dec 8, 2017

tacaswell commented on Dec 13, 2017

efiring commented on Dec 13, 2017

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