I am writing a GUI application in wxPython and using MPL that plots figures,
saves them to image files, and then closes them all from within a thread to
keep the GUI responsive. Using the Enthought 2.3 install I would
sporatically have crashes that were hard to reproduce, but now that I've
upgrade to Enthought 2.5 (Python 2.5 and MPL 0.91.2.0001) it started
throwing exceptions when attempting to close a figure that I don't
understand. I've created an example script that excites the exception. I'm
not sure if the syptoms are a combination of problems caused by my use of
threads but this problem does not occur if threading is removed from the
script. I've read of others experiencing memory leaks and such when closing
figures, but no situations quite like this.
I am working from a desktop in Windows XP and I use the WXAgg backend.
Does anyone have any ideas, or any feedback on my use of threads? Thanks,
Josh
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#!/usr/bin/python
import wx
import time
from threading import Thread
import matplotlib
matplotlib.interactive(False)
matplotlib.use('WXAgg')
import matplotlib.pylab
class TestThread(Thread):
def __init__(self, notify_window):
Thread.__init__(self)
def run(self):
while True: # Continuous loop that plots and destroys a figure
matplotlib.pylab.figure(1)
matplotlib.pylab.plot(range(0,5), range(0,5))
matplotlib.pylab.show()
time.sleep(1)
matplotlib.pylab.close(1) ### ERROR OCCURS HERE
class MainPanel(wx.Panel):
def __init__(self, *args, **kwargs):
wx.Panel.__init__(self, *args, **kwargs)
self.test_thread = None
# GUI objects and bindings
self.run_test_button = wx.Button(self, -1, "Run")
self.top_sizer = wx.BoxSizer(wx.VERTICAL)
self.top_sizer.Add(self.run_test_button, 0, wx.EXPAND|wx.ALL,
border=2)
self.SetSizer(self.top_sizer)
self.Bind(wx.EVT_BUTTON, self.run_test_button_bind, id =
self.run_test_button.GetId())
### Binding Methods
def run_test_button_bind(self, event):
self.test_thread = TestThread(self)
self.test_thread.start()
#self.test_thread.run()
class MainFrame(wx.Frame):
def __init__(self, *args, **kwargs):
mFrame = wx.Frame.__init__(self, *args, **kwargs)
self.mPanel = MainPanel(self, -1)
class mainApp(wx.App):
def OnInit(self):
self.frame = MainFrame(None, title="Test", size=wx.Size(100, 100))
self.frame.Show()
self.SetTopWindow(self.frame)
return True
if __name__ == "__main__":
app = mainApp()
app.MainLoop()
--------------------------------------------------------------------------------------------------
Exception in thread Thread-1:
Traceback (most recent call last):
File "C:\Python25\lib\threading.py", line 486, in __bootstrap_inner
self.run()
File ".\test.py", line 22, in run
matplotlib.pylab.close(1) ### ERROR OCCURS HERE
File
"C:\python25\lib\site-packages\matplotlib-0.91.2.0001-py2.5-win32.egg\matplotlib\pyplot.py",
line 245, in close
_pylab_helpers.Gcf.destroy(arg)
File
"C:\python25\lib\site-packages\matplotlib-0.91.2.0001-py2.5-win32.egg\matplotlib\_pylab_helpers.py",
line 28, in destroy
figManager.destroy()
File
"C:\python25\lib\site-packages\matplotlib-0.91.2.0001-py2.5-win32.egg\matplotlib\backends\backend_wx.py",
line 1406, in destroy
self.frame.Destroy()
File
"C:\python25\lib\site-packages\matplotlib-0.91.2.0001-py2.5-win32.egg\matplotlib\backends\backend_wx.py",
line 1365, in Destroy
wxapp.Yield()
File
"C:\python25\lib\site-packages\wxpython-2.8.4.0.0003_s-py2.5-win32.egg\wx\_core.py",
line 7119, in Yield
return _core_.PyApp_Yield(*args, **kwargs)
PyAssertionError: C++ assertion "wxThread::IsMain()" failed at
..\..\src\msw\evtloop.cpp(244) in wxEventLoop::Dispatch(): only the main
thread can process Windows messages
--
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