title: Matplotlib OverflowError: Allocated too many blocks
body: <p>I am plotting three sets of roughly 20 time series. Each time series has 1.8 million points and I am plotting them separately. In order to reduce execution time (because I found out that the figure() function is quite time consuming), I open one figure only, plot and then clean it for the next time series. Something like:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  
  fig = plt.figure() # open a figure for plotting
  for v in range(nfigs):
      # here I build the x and y vectors from the raw data
      # and also the figname string
      plt.plot(x, y, linewidth=0.3)
      plt.title('a title')
      plt.xlabel('x-label')
      plt.ylabel('y-label')
      plt.grid()
      plt.draw()
      plt.savefig(figname)
      plt.clf()
  plt.close() # close the figure after the job is done
  </code></pre>
  
  <p>All the plots are saved ok except for one in particular in all the data sets which gives me the following error (edited the file paths for privacy):</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 540, in runfile
      execfile(filename, namespace)
    File "batch.py", line 142, in &lt;module&gt;
      main(fn)
    File "batch.py", line 94, in main
      plt.savefig(figname+'_'+nn+'.png')
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\pyplot.py", line 561, in savefig
      return fig.savefig(*args, **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\figure.py", line 1421, in savefig
      self.canvas.print_figure(*args, **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\backends\backend_qt4agg.py", line 167, in print_figure
      FigureCanvasAgg.print_figure(self, *args, **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\backend_bases.py", line 2220, in print_figure
      **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\backends\backend_agg.py", line 505, in print_png
      FigureCanvasAgg.draw(self)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\backends\backend_agg.py", line 451, in draw
      self.figure.draw(self.renderer)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
      draw(artist, renderer, *args, **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\figure.py", line 1034, in draw
      func(*args)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
      draw(artist, renderer, *args, **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\axes.py", line 2086, in draw
      a.draw(renderer)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
      draw(artist, renderer, *args, **kwargs)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\lines.py", line 562, in draw
      drawFunc(renderer, gc, tpath, affine.frozen())
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\lines.py", line 938, in _draw_lines
      self._lineFunc(renderer, gc, path, trans)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\lines.py", line 978, in _draw_solid
      renderer.draw_path(gc, path, trans)
    File "~\AppData\Local\Continuum\Anaconda\lib\site-packages\matplotlib\backends\backend_agg.py", line 145, in draw_path
      self._renderer.draw_path(gc, path, transform, rgbFace)
  OverflowError: Allocated too many blocks
  </code></pre>
  
  <p>The time series that triggers this error has absolutely nothing special about it, I have checked it with a simple show() instead of savefig(). It is neither the first one nor the last one (in roughly 60 time series) but it is enough to break my script. Help on this is much appreciated!</p>