wxpython ProgressDialog segmentation fault (lin, not win)

Question

Up until recently, a code I have been working on and running in both Windows (8) and Linux (XUbuntu 14.04) environments started to give segmentation faults upon creating a wx ProgressDialog, but only on the latter platform. This minimal code sample illustrates the problem:

#!/usr/bin/python

import wx
import time

class MyFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, 'test ',
         pos=(200, 100), size=(120, 160))

        self.Show(True)
        but = wx.Button(self, -1,label="Click me!", pos=(10,10), size=(100,100))
        but.Bind(wx.EVT_BUTTON, self.click)

    def click(self,evt):
        progress_dlg = wx.ProgressDialog('Progress', 'Testing...', -1,
                                             style=wx.PD_ELAPSED_TIME)

        for i in range(10):
           time.sleep(0.5)
           progress_dlg.Pulse()

        progress_dlg.Destroy()


if __name__ == "__main__":
    application = wx.App(False)
    window = MyFrame()
    application.MainLoop()

This code works fine on my Windows machine, but not on our Linux server. Presumably the sudden change is related to some recent library update. The exact error message is:

Segmentation fault (core dumped)

and the same happens when running the code with pdb.

I am unsure how to proceed to identify and fix the problem and would welcome any suggestions. Thanks in advance.

Can't say off the bat what the problem is because it's working here. But I'd try putting a `print('ID')` at basically every row to identify the row where your code brings up the segmentation fault, I'm guessing in the `Pulse()` function. And also run `python -m trace --trace myscript.py` — Torxed, Aug 07 '15 at 13:58
For future references check these as well: http://stackoverflow.com/questions/1623039/python-debugging-tips and http://www.dalkescientific.com/writings/diary/archive/2005/04/20/tracing_python_code.html — Torxed, Aug 07 '15 at 13:59
Thanks, I'll dive in to these, there are bound to be some things I have not tried yet. And yes, Pulse() is causing the segmentation fault. — Asellus aquaticus, Aug 07 '15 at 14:58

Mike Driscoll · Accepted Answer · 2015-08-07T18:48:51.870

The call to Pulse() does seem to cause it to break on my system as well. I am using wxPython 2.8.12.1 with Python 2.7 on Xubuntu 14.04. If I swap out Pulse for Update, it works fine:

import wx
import time

class MyFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, 'test ',
         pos=(200, 100), size=(120, 160))

        self.Show(True)
        but = wx.Button(self, -1,label="Click me!", pos=(10,10), size=(100,100))
        but.Bind(wx.EVT_BUTTON, self.click)

    def click(self,evt):
        progress_dlg = wx.ProgressDialog('Progress', 'Testing...', -1,
                                             style=wx.PD_ELAPSED_TIME)

        for i in range(10):
            time.sleep(0.5)
            progress_dlg.Update(i)

        progress_dlg.Destroy()


if __name__ == "__main__":
    application = wx.App(False)
    window = MyFrame()
    application.MainLoop()

UPDATE - I just tried your code with wxPython 3.0.0.0 and it gives me the following traceback:

Traceback (most recent call last):
  File "test.py", line 15, in click
    style=wx.PD_ELAPSED_TIME)
  File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_windows.py", line 3764, in __init__
  _windows_.ProgressDialog_swiginit(self,_windows_.new_ProgressDialog(*args, **kwargs))
wx._core.PyAssertionError: C++ assertion "pos <= m_rangeMax" failed at  ../src/gtk/gauge.cpp(95) in SetValue(): invalid value in wxGauge::SetValue()

This gave me the idea that you need to set the maximum value when you instantiate your ProgressDialog. I tried that and it works. Just change that line to the following:

progress_dlg = wx.ProgressDialog('Progress', 'Testing...', maximum=10,
                                         style=wx.PD_ELAPSED_TIME)

Yep, that parameter is not an ID value like the usual wx API, and the GTK widgets used do not safely handle negative numbers for the value setting. — RobinDunn, Aug 07 '15 at 19:03

wxpython ProgressDialog segmentation fault (lin, not win)

1 Answers1