Re: [matplotlib-devel] Possible bug in matplotlib.cbook.CallbackRegistry
Here is a bit more detail and a simple example.
The example below places red squares in an axes. When the user clicks on an
existing red square - another square is created and added. When the user hits
any key a square is deleted from the axes. The error is triggered by clicking
on the red square and then hitting any key, and then clicking a red square
again.
Diagnosis:
By monitoring cbook.py line 235 and cbook.py line 263 it can be seen that after
the second mouse click (following one of the squares being deleted), that the
process() function builds a loop and begins handling the button press
callbacks. Note that there is a dead reference coming later in this list. The
first callback involves another square being created and the connect() method
being called. In the connect() call - the dead reference is deleted from the
callback list. Now upon returning to the process() callback this dead
reference is no longer in the callback list and a Key Exception is triggered
once it gets to it in the loop.
Problem:
There are two locations where dead references are cleared from the callback
list. When these loops get intermingled - as the case with a callback leading
to another connect mid-loop - the exception occurs when both loops attempt to
delete the dead reference.
Possible Solutions:
1. Trap the KeyException at the point of attempting to delete it from the list
in both places.
2. Place the dead reference check and deletion within a single method ... and
perform this check at beginning of the process() and connect() methods before
processing callbacks.
Sample Code
import matplotlib
matplotlib.use('WXAGG')
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg
from matplotlib.pyplot import Figure, Axes, Rectangle
import wx
import random
class SquareManager(object):
def __init__(self, axes):
self.axes = axes
self.canvas = axes.figure.canvas
self.squares = []
self.last_x = 0
self.canvas.mpl_connect('key_press_event', self.on_key_press)
def add_square(self):
self.last_x += .1
s = Square(self, self.axes, [self.last_x, .4],
.05, .05, facecolor='red', edgecolor='black')
self.squares.append(s)
self._refresh()
def on_key_press(self, evt):
if len(self.squares) == 0: return
# delete the first square - results in no error
# self.squares[0].remove()
# del self.squares[0]
# delete the last square - results in the error
self.squares[-1].remove()
del self.squares[-1]
self._refresh()
def _refresh(self):
self.canvas.draw()
class Square(Rectangle):
def __init__(self, manager, axes, *args, **kwds):
Rectangle.__init__(self, *args, **kwds)
axes.add_patch(self)
self.manager = manager
axes.figure.canvas.mpl_connect('button_press_event', self.selected)
def selected(self, evt):
within, _ = self.contains(evt)
if within:
self.manager.add_square()
app = wx.PySimpleApp()
frame = wx.Frame(None)
fig = Figure()
canvas = FigureCanvasWxAgg(frame, -1, fig)
a = Axes(fig, [.1, .1, .8, .8])
fig.add_axes(a)
sm = SquareManager(a)
sm.add_square()
frame.Show()
app.MainLoop()
# To demonstrate the error:
#
# 1. click on red sqaure
# 2. press any key
# 3. click on red sqaure again
--
The demand for IT networking professionals continues to grow, and the
demand for specialized networking skills is growing even more rapidly.
Take a complimentary Learning@Cisco Self-Assessment and learn
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Re: [matplotlib-devel] Possible bug in matplotlib.cbook.CallbackRegistry
I've run into this same issue in the past, and have it "fixed" in my
own local copy of matplotlib. I just placed a check to make sure that
cid actually was in the callbacks for s before deleting it.
That is quite possibly a band-aid; I never looked far enough in to
see. But it is possibly another way of fixing the problem.
def process(self, s, *args, **kwargs):
"""
process signal *s*. All of the functions registered to receive
callbacks on *s* will be called with *\*args* and *\*\*kwargs*
"""
if s in self.callbacks:
for cid, proxy in self.callbacks[s].items():
# Clean out dead references
if proxy.inst is not None and proxy.inst() is None:
if cid in self.callbacks[s]: #<--- here
del self.callbacks[s][cid]
else:
proxy(*args, **kwargs)
On Tue, Oct 25, 2011 at 1:09 PM, wrote:
> Here is a bit more detail and a simple example.
>
> The example below places red squares in an axes. When the user clicks on an
> existing red square - another square is created and added. When the user hits
> any key a square is deleted from the axes. The error is triggered by
> clicking on the red square and then hitting any key, and then clicking a red
> square again.
>
> Diagnosis:
> By monitoring cbook.py line 235 and cbook.py line 263 it can be seen that
> after the second mouse click (following one of the squares being deleted),
> that the process() function builds a loop and begins handling the button
> press callbacks. Note that there is a dead reference coming later in this
> list. The first callback involves another square being created and the
> connect() method being called. In the connect() call - the dead reference is
> deleted from the callback list. Now upon returning to the process() callback
> this dead reference is no longer in the callback list and a Key Exception is
> triggered once it gets to it in the loop.
>
> Problem:
> There are two locations where dead references are cleared from the callback
> list. When these loops get intermingled - as the case with a callback
> leading to another connect mid-loop - the exception occurs when both loops
> attempt to delete the dead reference.
>
> Possible Solutions:
> 1. Trap the KeyException at the point of attempting to delete it from the
> list in both places.
>
> 2. Place the dead reference check and deletion within a single method ... and
> perform this check at beginning of the process() and connect() methods before
> processing callbacks.
>
>
> Sample Code
>
>
> import matplotlib
> matplotlib.use('WXAGG')
>
> from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg
> from matplotlib.pyplot import Figure, Axes, Rectangle
>
> import wx
> import random
>
> class SquareManager(object):
> def __init__(self, axes):
> self.axes = axes
> self.canvas = axes.figure.canvas
> self.squares = []
> self.last_x = 0
>
> self.canvas.mpl_connect('key_press_event', self.on_key_press)
>
> def add_square(self):
> self.last_x += .1
> s = Square(self, self.axes, [self.last_x, .4],
> .05, .05, facecolor='red', edgecolor='black')
> self.squares.append(s)
> self._refresh()
>
> def on_key_press(self, evt):
> if len(self.squares) == 0: return
>
> # delete the first square - results in no error
> # self.squares[0].remove()
> # del self.squares[0]
>
> # delete the last square - results in the error
> self.squares[-1].remove()
> del self.squares[-1]
>
> self._refresh()
>
> def _refresh(self):
> self.canvas.draw()
>
>
> class Square(Rectangle):
> def __init__(self, manager, axes, *args, **kwds):
> Rectangle.__init__(self, *args, **kwds)
> axes.add_patch(self)
>
> self.manager = manager
> axes.figure.canvas.mpl_connect('button_press_event', self.selected)
>
> def selected(self, evt):
> within, _ = self.contains(evt)
> if within:
> self.manager.add_square()
>
>
> app = wx.PySimpleApp()
> frame = wx.Frame(None)
> fig = Figure()
> canvas = FigureCanvasWxAgg(frame, -1, fig)
> a = Axes(fig, [.1, .1, .8, .8])
> fig.add_axes(a)
>
> sm = SquareManager(a)
> sm.add_square()
>
> frame.Show()
> app.MainLoop()
>
>
> # To demonstrate the error:
> #
> # 1. click on red sqaure
> # 2. press any key
> # 3. click on red sqaure again
>
>
>
>
>
>
>
>
>
> --
> The demand for IT networking professionals continues to grow, and the
> demand for specialized networking skills is growing even more rapidly.
> Take a complimentary Learning@Cisco Self-Assessment and learn
> about Cisco certifications, training, and career opportunities.
> http://p.sf.net/sfu/cisco-dev2dev
> _
Re: [matplotlib-devel] Possible bug in matplotlib.cbook.CallbackRegistry
Daniel - Yes that works. In my case - I hate to edit any existing third party code bases - or it bites me later when I upgrade. For now - I simply do my own dead reference clean up externally when doing the deletes. Really, that would be the same as just doing a disconnect - but for other reasons (not worth going into detail here) - I prefer deleting and not having to know all of the connection points. My solution ensures that the dead references aren't around later. I mainly wanted to get it out into the devel community - get smart eyeballs on it - and hope that it gets addresses in a future release. It will likely be a fairly straightforward fix - as you show. -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
[matplotlib-devel] which to fork from?
For small bugfixes, am I supposed to fork from v1.1.x, or master? -- Daniel Hyams dhy...@gmail.com -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
Re: [matplotlib-devel] which to fork from?
On Tuesday, October 25, 2011, Daniel Hyams wrote: > For small bugfixes, am I supposed to fork from v1.1.x, or master? > V1.1.x is the maintenance branch. Master is for new features. When bugfixes are made and merged to v1.1.x, we then merge it to master. Ben Root -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
Re: [matplotlib-devel] which to fork from?
On Tue, Oct 25, 2011 at 3:52 PM, Daniel Hyams wrote: > For small bugfixes, am I supposed to fork from v1.1.x, or master? I say 'master' (Mike's been pushing some things to v1.1.x, but as he said in a comment to #551, "Pushed to v1.1.x since this is pretty serious yet simple-to-fix bug -- it should be on the maintenance branch.") best, -- Paul Ivanov 314 address only used for lists, off-list direct email at: http://pirsquared.org | GPG/PGP key id: 0x0F3E28F7 -- The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Cisco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev ___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
