Amara 2.0.0_alpha6 XML bindery leaks memory

[kcgen]

bindery.parse(...) leaks roughly 200x more memory than the size of the XML document that it's parsing. A 1KB document leaks about 200KB of RAM, which quickly adds up for long running processes performing repeated parsing.

In addition, each parse(...) call adds un-collectable objects to Python's variable reference tracking system, and adds O(1) CPU processing time overhead - perhaps because of the ever-growing reference-tracking load.

How to reproduce:

Python 2.7.6 (default, May  7 2014, 07:34:22) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gc 
>>> len(gc.get_objects())
3803
>>> from amara import bindery
>>> len(gc.get_objects())
12113
>>> bindery.parse(open('test.xml'))
<entity at 0xb2ee60: 1 children>
>>> len(gc.get_objects())
12285
>>> bindery.parse(open('test.xml'))
<entity at 0xbed710: 1 children>
>>> len(gc.get_objects())
12832
>>> bindery.parse(open('test.xml'))
<entity at 0xbf6f80: 1 children>
>>> len(gc.get_objects())
12764
>>> bindery.parse(open('test.xml'))
<entity at 0xbf6050: 1 children>
>>> len(gc.get_objects())
13297
>>> bindery.parse(open('test.xml'))
<entity at 0xbf3830: 1 children>
>>> len(gc.get_objects())
13229
>>> bindery.parse(open('test.xml'))
<entity at 0xbf37a0: 1 children>
>>> len(gc.get_objects())
13762
>>> bindery.parse(open('test.xml'))
<entity at 0xcd60e0: 1 children>
>>> len(gc.get_objects())
13707
>>> bindery.parse(open('test.xml'))
<entity at 0xbf6050: 1 children>
>>> len(gc.get_objects())
14240

Compare this to a well behaved parser:

Python 2.7.6 (default, May  7 2014, 07:34:22) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gc
>>> import xml.etree.cElementTree as ET
>>> len(gc.get_objects())
4289
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a0197b0>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019e10>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019990>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019ed0>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019870>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019a20>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019db0>
3849
>>> ET.parse(open('test.xml')).getroot(); len(gc.get_objects())
<Element '{http://www.w3.org/2005/Atom}feed' at 0x7fa03a019ae0>
3849
>>>