On 2/3/2011 3:13 PM, Eric Firing wrote:
> On 02/03/2011 01:02 PM, Christoph Gohlke wrote:
>>
>>
>> On 2/3/2011 2:44 PM, Eric Firing wrote:
>>> On 02/03/2011 12:28 PM, Christoph Gohlke wrote:
>>>>
>>>>
>>>> On 2/3/2011 2:15 PM, Eric Firing wrote:
>>>>> On 02/03/2011 11:30 AM, Robert Abiad wrote:
>>>>>> On 2/3/2011 10:06 AM, Eric Firing wrote:
>>>>>>> On 02/02/2011 10:17 PM, Eric Firing wrote:
>>>>>>>> On 02/02/2011 08:38 PM, Robert Abiad wrote:
>>>>>>>>>
>>>>>>>> [...]
>>>>>>>>> I'll put it in as an enhancement, but I'm still unsure if there is a
>>>>>>>>> bug in
>>>>>>>>> there as well. Is there something I should be doing to clear memory
>>>>>>>>> after the
>>>>>>>>> first figure is closed other than close()? I don't understand why
>>>>>>>>> memory usage
>>>>>>>>> grows each time I replot, but I'm pretty sure it isn't desireable
>>>>>>>>> behavior. As
>>>>>>>>> I mentioned, this effect is worse with plot.
>>>>>>>>>
>>>>>>>>> So is this a bug or improper usage?
>>>>>>>>
>>>>>>>> I'm not quite sure, but I don't think there is a specifically
>>>>>>>> matplotlib
>>>>>>>> memory leak bug at work here. Are you using ipython, and if so, have
>>>>>>>> you
>>>>>>>> turned off the caching? In its default mode, ipython keeps lots of
>>>>>>>> references, thereby keeping memory in use. Also, memory management and
>>>>>>>> reporting can be a bit tricky and misleading.
>>>>>>>>
>>>>>>>> Nevertheless, the attached script may be illustrating the problem. Try
>>>>>>>> running it from the command line as-is (maybe shorten the loop--it
>>>>>>>> doesn't take 100 iterations to show the pattern) and then commenting
>>>>>>>> out
>>>>>>>> the line as indicated in the comment. It seems that if anything is done
>>>>>>>> that adds ever so slightly to memory use while the figure is displayed,
>>>>>>>> then when the figure is closed, its memory is not reused. I'm puzzled.
>>>>>>>
>>>>>>> I wasn't thinking straight--there is no mystery and no memory leak.
>>>>>>> Ignore my example script referred to above. It was saving rows of the z
>>>>>>> array, not single elements as I had intended, so of course memory use
>>>>>>> was growing substantially.
>>>>>>>
>>>>>>> Eric
>>>>>>>
>>>>>>
>>>>>> You may not see a memory leak, but I still can't get my memory back
>>>>>> without killing python. I
>>>>>> turned off the ipython caching and even ran without iPython on both
>>>>>> Windows and Ubuntu, but when I
>>>>>> use imshow(), followed by close('all') and another imshow(), I run out
>>>>>> of memory. I can see from
>>>>>> the OS that the memory does not come back after close() and that it
>>>>>> grows after the second imshow().
>>>>>>
>>>>>> Any other ideas? Looks like a bug to me otherwise.
>>>>>
>>>>> Except that I tried the same things and did not get quite the same
>>>>> result. Let's track this down. Please try the attached script, and see
>>>>> if the memory usage grows substantially, or just oscillates a bit.
>>>>>
>>>>> Eric
>>>>>
>>>>
>>>>
>>>> One thing I noticed is that if I add a "def __del__(self): print 'del'"
>>>> to image._AxesImageBase, it never gets called. _AxesImageBase keeps
>>>> float64 and uint8 rgba images in a cache, which is never freed.
>>>
>>> Adding a __del__ method defeats (or blocks) the garbage collection.
>>>
>>
>> Sorry, never heard of that. I thought __del__() is called when the
>> reference count reaches 0.
>
> It is, but if there are circular reference chains (cycles--and mpl is
> full of them) then the garbage collector has to identify them and remove
> them. If it encounters a __del__ it stops and leaves that cycle alone.
>
My understanding is that if there is a circular reference then the
refcount will not be zero anyway. In this case _AxesImageBase instances
and their image caches will never be deleted by the gc (__del__ method
present or not) unless the circle is broken. When the interpreter quits
things are deleted by other means. I don't know matplotlib code good
enough to fix this and will instead work on reducing the memory overhead
needed to plot an image. In the meantime it could help to explicitly
delete the image cache when a plot closes or to avoid caching altogether.
Christoph
> Eric
>
>>
>> Christoph
>>
>>> Since self._imcache is an instance attribute, when the instance is no
>>> longer referenced, it should get garbage-collected, provided there is no
>>> __del__ method.
>>>
>>> Eric
>>>
>>>>
>>>> Christoph
>
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