[IPython-dev] Qt console unusable, any ideas?

Fernando Perez fperez.net at gmail.com
Fri Nov 4 17:09:46 EDT 2011

On Fri, Nov 4, 2011 at 2:05 PM, Mark Voorhies <mark.voorhies at ucsf.edu> wrote:
> If I set 'backend: GTK' in ~/.matplotlib/matplotlibrc
> and launch "ipython qtconsole --pylab"
> then matplotlib.pyplot.get_backend() reports "GTKAgg".
> In this configuration I am getting the dead kernel dialog,
> but not in a predictable way (e.g., sometimes it is enough
> to import matplotlib.pyplot and try to call get_backend,
> sometimes I need to do a bit of real work before seeing
> the message).
> The problem doesn't appear to repeat with my default (TkAgg backend)
> configuration.
> I've been using the TkAgg backend with the qtconsole for my day-to-day
> work for the last few weeks without seeing the dead kernel dialog or
> noticing slow response.

The dead kernel dialog only appears if the delay is > 3s, and I think
the typical delays I'm seeing hover right around that, so sometimes it
happens and others not. But dead kernel dialog or not, there's always
a very sluggish response to all actions, and for example call tooltips
never appear.

This does not happen in the terminal ipython (with pylab/gtk).  So
it's some interaction between our gtk event loop handling and the
kernel code.  Weird...



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