I'm on to something -- some callbacks are being created that are never
disconnected.
In Line2D.set_axes:
self._xcid = ax.xaxis.callbacks.connect('units', self.recache_always)
gets called twice. This is problematic because the id of the first
connection is simply lost. Also, there doesn't seem to be any code to
attempt to remove either of them.
I'm looking into it further -- forcibly deleting these callbacks reduces
the reference count on the line object, but doesn't seem to completely
eliminate the leak.
Mike
On 05/28/2010 10:12 AM, John Hunter wrote:
> On Fri, May 28, 2010 at 3:18 AM, Pearu Peterson<pe...@cens.ioc.ee> wrote:
>
>> Hi,
>>
>> In an application that updates a plot with
>> new experimental data, say, every second and the experiment
>> can last hours, I have tried two approaches:
>> 1) clear axes and plot new experimental data - this is
>> slow and takes too much cpu resources.
>> 2) remove lines and plot new experimental data - this is
>> fast enough but unfortunately there seems to be a memory
>> leakage, the application runs out of memory.
>>
>> Here follows a simple script that demonstrates the
>> leakage problem:
>>
>> #
>> import numpy
>> from numpy.testing.utils import memusage
>> import matplotlib.pyplot as plt
>> x = range (1000)
>> axes1 = plt.figure().add_subplot( 111 )
>> y = numpy.random.rand (len (x))
>> while 1:
>> if 1:
>> # leakage
>> for line in axes1.lines:
>> if line.get_label ()=='data':
>> line.remove()
>> else:
>> # no leak, but slow
>> axes1.clear()
>> axes1.plot(x, y, 'b', label='data')
>> print memusage (), len (axes1.lines)
>> #eof
>>
>> When running the script, the memory usage
>> is increasing by 132 kbytes per iteration, that is,
>> with an hour this example application will consume
>> 464MB RAM while no new data has been generated. In real
>> application this effect will be even worse.
>>
>> So, I am looking for an advice how to avoid
>> this memory leakage without clearing axes.
>>
> Hey Pearu -- thanks for the report. We'll try and track down and fix
> this leak. In the interim, would an acceptable work around for you be
> to *reuse* an existing line by calling set_data on it. That way you
> wouldn't have to do the add/remove that is causing your leak. Have
> you confirmed this leak on various backends (eg Agg, PDF, PS)?
>
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--
Michael Droettboom
Science Software Branch
Space Telescope Science Institute
Baltimore, Maryland, USA
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