matplotlib-devel Mailing List for matplotlib

In 2007, two different major memory leaks have been identified:
1) Eric Pellegrini showed that a loop over figure(); close() leaks. I 
have verified that this occurs with any interactive backend, but not 
with non-interactive backends. This may be the same problem that was 
reported in other messages, such as one by Dylan Passmore in January.
2) There is a recent thread "Re: Memory leak in basemap or matplotlib" 
showing that even with a non-interactive backend, a seemingly-pointless 
call to cla() is needed to prevent a leak.
I would like to suggest that we try harder to solve these problems ASAP. 
 This kind of malfunctioning at the core of mpl worries me.
I have spent quite a bit of time trying to figure out (1), and I have 
tracked it down to the NavigationToolbar2. Eliminate the toolbar by 
putting None in the rc slot, and the memory leak vanishes. It looks to 
me like some explicit call to a destroy method may be needed to 
dismantle the toolbar when a figure is closed and/or deleted. I suspect 
that each gui toolkit is keeping references to components, and the 
toolbar is not getting the word when the window is destroyed. 
gc.garbage verifies that the toolbar components are what get left behind.
So, I hope a gui toolkit backend wizard can step forward and say, "Of 
course, we just need to put a __del__ method here with a call to 
destroy()", or something like that.
I have spent much less time on (2), and made no progress.
We are relying very heavily on the gc--mpl has cyclic references all 
over the place. Is anyone sure that we don't need explicit gc support 
in any of the extension code? Can *everything* in the extension code be 
handled correctly with reference counting? Is this independent of how 
things defined in extension code are used at the python level?
It is not clear to me that gc debugging methods even allow one to see 
problems in extension code that do not have some degree of gc support. 
The standard documentation of the gc module and the gc C API is minimal.
Eric

I've got a routine, attached, which is simple and fast, and returns very nicely spaced ticks along with the number of minor ticks. It's an old algorithm from a '73 ACM article, but tried and true. I suppose this should be implemented as a Locator, but I'm not very familiar with the pylab code. Perhaps someone could demonstrate the appropriate way?
-- 
Tom Holroyd, Ph.D.
We experience the world not as it is, but as we expect it to be.

On 3/26/07, Eric Firing <ef...@ha...> wrote:
> Popping the 'a' entry inside the function did not affect the dictionary
> that was passed in; it evidently gets copied automatically.
>
> Am I missing something? Or should I go ahead and strip out the extra
> copies and modify the corresponding advice in CODING_GUIDE?
Well, that was certainly a surprise to me -- yep all the copying of
**kwargs can be eliminated and the CODING_GUIDE updated. Thanks for
discovering this and pointing it out!
JDH