[IPython-dev] ipython slowdown with qt


While I can reproduce the issue using %gui qt I can also reproduce it with the WX backend (%qui wx) with more or less the same symptoms. However, I don’t see the issue with either of the ‘tk’ or the ‘osx’ backends. And yes the issue is reproducible in a python installation without any mpl installed.


On Fri, Aug 15, 2014 at 9:22 PM, Eric Firing <efiring@…229…> wrote:

On 2014/08/15, 9:37 AM, Derek Homeier wrote:

When using MPL with ipython —pylab and the Quartz version of PyQT4,

the interpreter seems to be slow down extremely after running for a

little while. Weirdly this is not connected to any graphics display

and in fact happens even without any plotting window opened, i.e. the

ipython shell just randomly becomes completely unresponsive and hangs

for several seconds on simple tasks like typing or navigating through

history. The plotting itself actually does not appear to perform any

worse than it used to under Mountain Lion.

[I’m switching the subject because my comments below relate to ipython

and matplotlib, and are no longer Anaconda-specific.]


Thanks. A few days ago, when I switched from testing on linux to

testing on osx, exactly this ipython slowdown was happening to me–but I

lost track of what combination of versions and invocations was causing

it. Therefore I have been concentrating on the severe problem which

was, for me, 100% repeatable, and involved macosx backend, not Qt. I

expect the macosx-relatec problem will go away after Ilan uploads the

revised Anaconda ipython for python 3.

Now I find I can repeat the ipython problem on Homebrew python 3

(framework–with Quartz app) and Anaconda with the un-fixed ipython

(which is running without starting a Quartz app):

ipython --pylab=qt

Leave it alone for a bit. Try scrolling through history. Long delay,

even in responding to Ctrl-C. Evidently key events are stacking up and

not being processed. Now try:


%pylab qt

I see the slowdown with this, also. The response delay seems to get

worse with time. It renders the session unusable after only a few minutes.


%gui qt

And I still see it, so this appears to be a problem in ipython’s PyQt4

gui handling, not directly related to matplotlib. All on Mavericks,

running ipython from Apple’s terminal.


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