Re: [matplotlib-devel] Possible Bug

[John H. <jdh...@ac...>]

>>>>> "Joe" == Joe  <gar...@us...> writes:

    Joe> Hello devels, I chose to use matplotlib for a restaurant
    Joe> simulation.  It supplied all the features I needed and I was
    Joe> pleasantly surprised.  However the people I was doing this
    Joe> project for mentioned that the simulation slowed down to a
    Joe> crawl 10 or so minutes into the simulation.  It sounded like
    Joe> a memory leak to me so I investigated and found a 100 KB/sec
    Joe> leak in Windows (via the interpreter as well as frozen with
    Joe> py2exe) as well as in Linux.  I narrowed it down to a part of
    Joe> the code where I updated xlim and ylim via Axes::set_xlim,
    Joe> Axes::set_ylim.  Commenting that part out yielded no leak,

So you're doing animation right?  Are you using images, eg imshow?  I
just fixed a memory leak in image resizing that amounts to about
200K/resize -- the changes are in CVS.  Of course on windows it's hard
to test because the changes are in extension code, and require
building on win32.  The instructions for building on win32 are in the
file setupext.py.

If you are not using images, another place to look is in text caching.
text layout is expensive (to support arbitrary rotations, etc).  So I
cache the layout information in a dictionary "cached" in the text
module.  When you change the xlim/ylim, that would trigger a new
layout and an addition to the cache.  We need to add some
auto-clearing mechanisms to prevent the cache from growing w/o bound
but its not done yet.  I find it hard to believe, though, that this
would leak 100kb/sec.  Assuming a 20Hz frame rate, the leak is about
5kb/sec, and I don't think I'm caching that much info.

You can estimate the memory effect of the cached simply by commenting
out the line

        self.cached[key] = ret

in the matplotlib.text module.

What backend are you using?  Are you refreshing the same figure data,
or creating new figures?  More information would certainly help.....

    Joe> however I lost some critical functionality in my charts
    Joe> (which behave like the Windows Task Manager resource monitor
    Joe> graphs).  So I really need this fixed.  I will send shortly a
    Joe> test case which replicates the problem.

That would be great.

    Joe> Since the maintainer is out on vacation, I was also wondering
    Joe> if anyone knew enough about the internals of matplotlib that
    Joe> they could give me an idea of which modules (Python or
    Joe> otherwise) are affected by Axes::set_xlim and Axes::set_ylim.

I'm back.  I was in Rio for a couple of weeks and have suffered a 95
degree temperature drop returning to Chicago (sigh)...

JDH